Editing IPCC:AR6/WGII/Chapter-4 (section)

=== 4.7.1 Current Water-Related Adaptation Responses, Benefits, Co-benefits and Maladaptation ===

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AR5 ( [[#Jiménez%20Cisneros--2014|Jiménez Cisneros et al., 2014]] ) concluded that developing countries needed a larger share of adaptation investments for anticipatory adaptation in the water sector ( ''medium evidence, high agreement'' ) and that adaptive water management measures were critical in addressing climate-related uncertainty. [[#Noble--2014|Noble et al. (2014)]] listed various examples of adaptation options, and water-related adaptation featured prominently in almost all categories. They also discussed the challenges of developing metrics for measuring adaptation outcomes and stressed the importance of transformational adaptation instead of incremental adaptation. Finally, SR1.5 ( [[#de%20Coninck--2018|de Coninck et al., 2018]] ) made one of the first attempts to systematically assess the feasibility of adaptation options ( [[#Singh--2020|Singh and Basu, 2020]] ).

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==== 4.7.1.1 Current Water-Related Adaptation Responses ====

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We define an adaptation response as a water-related adaptation if the hazard is water-related (e.g., floods, droughts, extreme rainfall events, groundwater depletion, melting and thawing of cryosphere, Figure 4.25) or the adaptation intervention is water-related (e.g., irrigation, rainwater harvesting, soil moisture conservation, etc.). Adaptation responses were implemented across all water use sub-sectors assessed in this chapter ( [[#4.6|Section 4.6]] , Figure 4.23). Given the overall interest in assessing adaptations that documents outcomes, we limited our analysis to a set of 359 unique articles that measure outcomes of adaptation across pre-defined outcome categories (SM4.2, Table SM4.5; [[#Berrang-Ford--2021a|Berrang-Ford et al., 2021a]] ; [[#Mukherji--2021|Mukherji et al., 2021]] ). A total of 1054 adaptation responses were documented in the 359 case studies; these were categorised into 16 categories (Figure 4.22). These adaptation responses are not always specific to long-term climate change impacts (that is, changes in annual mean fluxes), but rather respond to changes in variability in the water cycle and specific water hazards. Adaptation to internal variability is needed to increase the resilience to projected water cycle changes because water cycle changes primarily manifest as changes in variability ( [[#Douville--2021|Douville et al., 2021]] ).

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[[File:391331e2154d2f21d45b885a41439933 IPCC_AR6_WGII_Figure_4_023.png]]

'''Figure 4.23 |''' '''Sectoral distribution of documented water-related adaptation responses (observed adaptation) across the 16 categories derived from Figure''' '''4.''' '''22.''' The quantity of evidence is derived from the number of papers in a particular adaptation response category where high is &gt; 40 papers, medium is 10–40 papers and low is &lt; 10 papers. Confidence in evidence relates to the way the article links outcomes of adaptation with the adaptation response. Category 1: studies causally link adaptation outcomes to the adaptation response by constructing credible counterfactuals; category 2: studies correlate responses and outcomes without causal attribution; category 3: studies describe adaptation outcomes without making any causal or correlation claims between adaptation outcomes and adaptation responses. ''High confidence'' : more than 67% of the studies fall in categories 1 and 2; ''medium confidence'' : 50–67% of the studies are in categories 1 and 2, and ''low confidence'' is less than 50% of studies are in categories 1 and 2.

There is ''high confidence'' that a significant share of water-related adaptations is occurring in the agriculture sector. Agriculture accounts for 60–70% of total water withdrawals ( [[#Hanasaki--2018|Hanasaki et al., 2018]] ; [[#Burek--2020|Burek et al., 2020]] ; [[#Müller%20Schmied--2021|Müller Schmied et al., 2021]] ) and supports the livelihoods of a large majority of people in the developing countries. Within the agriculture sector, there is ''high confidence'' in the quality and quantity of evidence of adaptation responses such as improved cultivars and agronomic practices, on-farm irrigation and water management and water and soil moisture conservation, and ''medium confidence'' , derived from ''robust evidence'' , and ''medium agreement'' for other most other adaptation responses (Figure 4.23 and Figure 4.24). Most of these adaptation case studies are from Asia and Africa, and agriculture is the predominant sector where most of these adaptation responses are being implemented ( ''high confidence'' ) ( [[#4.6.2|Section 4.6.2]] ). However, the sectoral nature of adaptation responses varies across continents. Agriculture is the most important sector in all continents, except Europe and Australasia, where most adaptation occurs in the urban sector ( ''high confidence'' ) (Figure 4.24).

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[[File:dcdbd382d3fd70d5ef2b5207cebfb86e IPCC_AR6_WGII_Figure_4_024.png]]

'''Figure 4.24 |''' '''Location of case studies on water-related adaptation which measure adaptation outcomes (''' '''''n''''' '''= 359) and their sectoral distribution across all regions.''' Circles denote the number of case studies in a particular location in the continent. The pie chart shows the sectors in which adaptation is taking place. The sectors correspond to water use sectors described in Sections 4.3, 4.5 and 4.6 of this chapter.

The top four adaptation responses in terms of frequency of documentation are changes in the cropping pattern and crop systems (145 responses), improved crop cultivars and agronomic practices (139 responses), irrigation and water management practices (115 responses) and water and soil conservation measures (102 responses). These top four responses provide several benefits such as higher incomes and yields, better water use efficiencies and related outcomes ( ''high confidence'' ) (Table 4.9 and Figure 4.27). However, those benefits are incremental, that is, they help improve crop production and incomes, at least in the short run, but may not automatically lead to transformative outcomes and climate risk reductions ( [[#Pelling--2015|Pelling et al., 2015]] ; [[#Fedele--2019|Fedele et al., 2019]] ). One way to move from incremental to transformative adaptation could be to invest gains from incremental adaptation in education and capacity building to improve overall adaptive capacity ( [[#Vermeulen--2018|Vermeulen et al., 2018]] ). Responses such as migration, including spontaneous and planned relocation, are also relatively well documented ( ''medium confidence'' ), as are responses such as collective action, training and capacity building and economic and financial measures for increasing adaptive capacities ( ''medium confidence'' ). These categories of adaptation can potentially lead to transformative outcomes, such as a shift to livelihoods that are less exposed to climate hazards. However, transformative pathways are not always straightforward ( [[#Pahl-Wostl--2020|Pahl-Wostl et al., 2020]] ) (Table 4.8).

'''Table 4.8 |''' Illustrative examples of case studies of water-related adaptation responses where outcomes were measured ( ''n'' = 359). These cases include instances where adaptation benefits were positive, negative or neutral. Examples also include studies with or without causal and correlation links between adaptation response and outcomes (categories 1, 2 and 3 studies as described in the caption of Figure 4.23). The purpose of the table is to provide a list of illustrative examples to showcase the wide range of adaptation responses that are being implemented. Table 4.9 zooms into examples where adaptation had positive benefits on any of the selected parameters described in [[#4.7.1.2|Section 4.7.1.2]] .

{| class="wikitable"
|-
! Name of the adaptation response (number of documented responses in that category)

! Description of adaptation response

! Sources

|-
| rowspan="3"| Changes in the cropping pattern and crop systems

(145 responses)

| Changes in cropping pattern; e.g., the introduction of sugarcane and rice in Costa Rica; crop diversification in Ethiopia and Zimbabwe; crop diversification in Tanzania

| [[#Singh--2014|Singh et al. (2014)]] ; [[#Warner--2015|Warner et al. (2015)]] ; Asmare et al. (2019); [[#Lalou--2019|Lalou et al. (2019)]] ; [[#Makate--2019|Makate et al. (2019)]]

|-
| Changes in the timing of sowing and harvesting, e.g., in China; India and Pakistan

| [[#Yu--2014|Yu et al. (2014)]] ; Macchi et al. (2015)

|-
| On-farm diversification, e.g., an integrated crop-livestock system in France

| [[#Havet--2014|Havet et al. (2014)]]

|-
| rowspan="2"| Improved crop cultivars and agronomic practices (139 responses)

| Improved crop cultivars, e.g., short-duration paddy varieties in Nepal; saline-tolerant rice cultivar in Bangladesh; drought-tolerant maize varieties in Malawi, Nigeria, Zimbabwe and Uganda

| [[#Kabir--2016|Kabir et al. (2016)]] ; [[#Wossen--2017|Wossen et al. (2017)]] ; [[#Khanal--2018a|Khanal et al. (2018a)]] ; [[#Makate--2019|Makate et al. (2019)]]

|-
| Improved agronomic practices, e.g., conservation agriculture to conserve soil moisture in Malawi and Tanzania; climate-smart agricultural practices in Zambia; alternate wetting and drying and direct seeding of rice in India

| Thierfelder et al. (2015); [[#Kimaro--2016|Kimaro et al. (2016)]] ; [[#Traore--2017|Traore et al. (2017)]] ; [[#Kakumanu--2019|Kakumanu et al. (2019)]]

|-
| rowspan="2"| Irrigation and water management practices

(115 responses)

| Irrigation, e.g., construction of local irrigation infrastructure in Chile; funding of community wells in Canada; drilling of borewells in Thailand; irrigation in Ethiopia; spate irrigation in Sudan; night-time irrigation scheduling to reduce evaporative demand in the UK

| [[#Hurlbert--2014|Hurlbert and Pittman (2014)]] ; Ferchichi et al. (2017); Rey et al. (2017); [[#Pak-Uthai--2018|Pak-Uthai and Faysse (2018)]] ; Fadul et al. (2019); Lemessa et al. (2019); [[#Lillo-Ortega--2019|Lillo-Ortega et al. (2019)]] ; [[#Torres-Slimming--2020|Torres-Slimming et al. (2020)]]

|-
| On-farm water management and water-saving technologies, e.g., use of surface pipes for irrigation water conveyance in China; drip irrigation in China; and use of water-saving measures in India

| [[#Hong--2017|Hong and Yabe (2017)]] ; [[#Tan--2017|Tan and Liu (2017)]] ; [[#Deligios--2019|Deligios et al. (2019)]] ; Rouabhi et al. (2019)

|-
| rowspan="4"| Water and soil conservation (102 responses)

| On-farm water and soil conservation measures, e.g., in Burkina Faso; terraces and contour bunds in Ethiopia

| West Colin et al. (2016); [[#Kosmowski--2018|Kosmowski (2018)]]

|-
| Water harvesting through on-sand dams in Kenya; ''in situ'' and ''ex situ'' water harvesting in Uganda and India

| Ngigi et al. (2018); [[#Sullivan-Wiley--2018|Sullivan-Wiley and Short Gianotti (2018)]] ; [[#Kalungu--2021|Kalungu et al. (2021)]]

|-
| Watershed conservation programmes, e.g., in Ethiopia

| Siraw et al. (2018)

|-
| Revival of water bodies; e.g., creation of artificial lakes in Portugal

| [[#Santos--2018|Santos et al. (2018)]]

|-
| rowspan="5"| Collective action, policies and institutions (95 responses)

| Collective action and cooperation; e.g., grassroots-level collective action for conflict resolution in Guatemala; collective decision to reduce water withdrawals during drought in Japan

| [[#Hellin--2018|Hellin et al. (2018)]] ; [[#Tembata--2018|Tembata and Takeuchi (2018)]]

|-
| Community-based adaptation in Bangladesh, community-based management of rangelands in Mongolia

| [[#Fernández-Giménez--2015|Fernández-Giménez et al. (2015)]] ; [[#Roy--2018|Roy (2018)]]

|-
| Local institutions, e.g., multi-stakeholder platforms for disaster risk reduction and agriculture in Peru and several African countries; Adaptation Learning Programme.

| [[#Mapfumo--2017|Mapfumo et al. (2017)]] ; [[#Lindsay--2018|Lindsay (2018)]]

|-
| Water dispute resolution; e.g., water conflict mitigation in Costa Rica.

| [[#Kuzdas--2016|Kuzdas et al. (2016)]]

|-
| Institutional and policy reforms; e.g., local water and land use planning instruments in Australia; the Dutch Delta Programme in the Netherlands; implementation of EU Flood Directives in Sweden

| Fallon and Sullivan (2014; Zevenbergen et al. (2015; [[#Hedelin--2016|Hedelin (2016)]]

|-
| rowspan="4"| Migration and off-farm diversification (92 responses)

| Spontaneous migration, e.g., voluntary relocation in the Solomon Islands and rural to urban migration in Ethiopia and Pakistan.

| [[#Birk--2014|Birk and Rasmussen (2014)]] ; [[#Iqbal--2018|Iqbal et al. (2018)]]

|-
| Employment and remittances, e.g., in Senegal.

| [[#Romankiewicz--2016|Romankiewicz et al. (2016)]]

|-
| Planned relocation; e.g., the Massive Southern Shaanxi Migration Programme in China; resettlement of flood-prone communities in Bangladesh.

| [[#Islam--2014|Islam et al. (2014)]] ; [[#Lei--2017|Lei et al. (2017)]]

|-
| Off-farm diversification; e.g., migration to towns and engaging in off-farm labour wage-earning in Niger, Ghana Bangladesh; shifting to non-pastoral livelihoods in Ethiopia

| Mussetta et al. (2016); Basupi et al. (2019)

|-
| rowspan="2"| Livestock and fishery-related (63 responses)

| Livestock related, e.g., livestock species diversification in Ethiopia and Kenya; insuring livestock in Pakistan; changes in range management practices in the USA.

| [[#Opiyo--2015|Opiyo et al. (2015)]] ; [[#Yung--2015|Yung et al. (2015)]] ; Wako et al. (2017); [[#Rahut--2018|Rahut and Ali (2018)]]

|-
| Fishery related, e.g., non-destructive fishery gears and techniques in Ghana and Tanzania

| [[#Yang--2019a|Yang et al. (2019a)]]

|-
| Training and capacity building (57 responses)

| Information, training and capacity building; e.g., climate information services in Kenya and Senegal; training contributed new learning about digging canals to avoid prolonged water logging in the Philippines; soil conservation training programme in Ethiopia

| [[#Bacud--2018|Bacud (2018)]] ; [[#McKune--2018|McKune et al. (2018)]] ; [[#Chesterman--2019|Chesterman et al. (2019)]]

|-
| rowspan="2"| Agroforestry and forestry-related responses (56 responses)

| Agroforestry-related measures in India, Kenya, Nigeria; farmer-managed natural regeneration (FMNR) in Ghana.

| [[#Weston--2015|Weston et al. (2015)]] ; [[#Pandey--2017|Pandey et al. (2017)]] ; [[#Fuchs--2019|Fuchs et al. (2019)]] ; [[#Okunlola--2019|Okunlola et al. (2019)]]

|-
| Forestry related; e.g., coastal afforestation by planting salinity-resistant trees in Bangladesh and Colombia

| Pandey et al. (2016); Barrucand et al. (2017); Barua et al. (2017)

|-
| rowspan="6"| Economic and financial incentives (54 responses)

| Insurance; rice crop insurance programme in Indonesia; agricultural insurance programme in South Africa.

| Dewi et al. (2018); Elum et al. (2018)

|-
| Micro-finance and credit programmes, e.g., in Bangladesh.

| Fenton et al. (2017b)

|-
| Social safety nets; e.g., food-based safety net programmes in Brazil, food for work programmes in Ethiopia.

| [[#Mesquita--2017|Mesquita and Bursztyn (2017)]] ; [[#Sain--2017|Sain et al. (2017)]] ; [[#Tesfamariam--2017|Tesfamariam and Hurlbert (2017)]] ; [[#Gao--2018|Gao and Mills (2018)]]

|-
| Subsidies and incentives, e.g., farm input subsidy programme in Malawi; financing programmes in Canada to help producers with resources to improve/maintain the quality of soil, water, biodiversity for drought mitigation.

| [[#Hurlbert--2014|Hurlbert (2014)]] ; [[#Kawaye--2018|Kawaye and Hutchinson (2018)]]

|-
| Water markets and tariffs; e.g., urban water tariffs in Zaragoza, Spain; informal groundwater markets in China.

| [[#Kayaga--2014|Kayaga and Smout (2014)]] ; [[#Zhang--2016b|Zhang et al. (2016b)]]

|-
| Payment for ecosystems services, e.g., in Mexico

| [[#Newsham--2018|Newsham et al. (2018)]]

|-
| IKLK based adaptations (41 responses)

| Use of TK of Konda Reddy’s in India to shift agroforestry practices; and among ''Khasia'' and Tripura communities in Bangladesh; use of local ecological knowledge is by small-scale fisher-farmers in the Amazon floodplains, Brazil; traditional water sharing system ‘ ''bethma'' ’ in Sri Lanka; indigenous methods of water harvesting in India

| [[#Sarkar--2015|Sarkar et al. (2015)]] ; [[#Burchfield--2016|Burchfield and Gilligan (2016)]] ; [[#Kodirekkala--2018|Kodirekkala (2018)]] ; [[#Ahmed--2019|Ahmed and Atiqul Haq (2019)]]

|-
| rowspan="5"| Flood risk reduction measures include (40 responses)

| Non-structural measures for flood management; e.g., changes in day-to-day practices in Indonesia; place-specific social structures in the UK.

| [[#Petzold--2018|Petzold (2018)]] ; [[#Bott--2019|Bott and Braun (2019)]]

|-
| Structural measures for flood management; improvement of the drainage system in Indonesia; flood walls in Beira, Mozambique; dredging and construction of culverts in Nigeria.

| [[#Bahinipati--2015|Bahinipati and Patnaik (2015)]] ; [[#Wijaya--2015|Wijaya (2015)]] ; Egbinola et al. (2017); [[#Spekker--2017|Spekker and Heskamp (2017)]]

|-
| Early warning systems; e.g., flood forecasting in Nepal, Indonesia, Nigeria.

| [[#Ajibade--2014|Ajibade and McBean (2014)]] ; Devkota et al. (2014); [[#Sari--2018|Sari and Prayoga (2018)]]

|-
| Flood-resilient housing; e.g., houses on stilts in Guyana, in Pakistan, Vietnam, Philippines.

| [[#Mycoo--2014|Mycoo (2014)]] ; [[#Ling--2015|Ling et al. (2015)]] ; [[#Abbas--2018|Abbas et al. (2018)]]

|-
| Wetland restoration; e.g., in the USA and Netherlands

| [[#Zevenbergen--2015|Zevenbergen et al. (2015)]] ; Pinto et al. (2018)

|-
| rowspan="3"| Urban water management (22 responses)

| Urban water management, e.g., incorporating low impact development and urban design features for sustainable urban drainage systems in Spain and Malaysia; demand management and tariff reforms in several European countries.

| [[#Flyen--2018|Flyen et al. (2018)]] ; [[#Rodríguez-Sinobas--2018|Rodríguez-Sinobas et al. (2018)]] ; Stavenhagen et al. (2018); [[#Chan--2019|Chan et al. (2019)]]

|-
| Green infrastructure; e.g., ecological stormwater management and re-naturalisation processes in Sweden; pavement watering in France, Ghana, India, Kenya, Bangladesh

| [[#Hendel--2015|Hendel and Royon (2015)]] ; [[#Wamsler--2016|Wamsler et al. (2016)]] ; [[#Tauhid--2018|Tauhid and Zawani (2018)]] ; Birtchnell et al. (2019)

|-
| Desalinisation for water supplies in Spain

| Martínez-Alvarez et al. (2016); Morote et al. (2019)

|-
| rowspan="2"| Energy-related adaptations (eight responses)

| Hydropower related; e.g., hydropower benefit-sharing in the Mekong basin and Nepal

| [[#Balasubramanya--2014|Balasubramanya et al. (2014)]] ; [[#Suhardiman--2014|Suhardiman et al. (2014)]] ; [[#Shrestha--2015|Shrestha et al. (2015)]]

|-
| Other renewable energy-related, e.g., “Raising Water and Planting Electricity project” in Taiwan province of China

| [[#Lin--2016|Lin and Chen (2016)]]

|-
| rowspan="2"| WaSH-related adaptations (five responses)

| Hand washing and hygiene, e.g., provision of latrines and washing hands with soap in Bangladesh

| [[#Dey--2019|Dey et al. (2019)]]

|-
| Safe drinking water and sanitation; e.g., piped water supply in China

| [[#Su--2017|Su et al. (2017)]]

|-
| Any other including coping strategies (20 responses)

| Reduction in consumption, selling off assets, etc.; e.g., selling of household property and livestock in Nigeria; consumption smoothing in Ghana; reducing consumption in Nepal

| [[#Musah-Surugu--2018|Musah-Surugu et al. (2018)]] ; [[#Rai--2019|Rai et al. (2019)]]

|}

'''Table 4.9 |''' Illustrative examples of adaptation responses and their benefits across different outcome indicators. All these studies are either category 1 or category 2 studies in that the link between adaptation response and the outcome is either causal or correlated with one another. These benefits notwithstanding, links of adaptation benefits to climate and associated risk reduction are not always clear. Some of these adaptation responses can have beneficial outcomes in one of the five parameters, but can have maladaptive outcomes in others.

{| class="wikitable"
|-
! Hazard

! Adaptation responses

! Outcome category

! Adaptation outcome

! Reference

|-
| Droughts, floods, and general climate impacts in Nepal

| Improved crop cultivars, agronomic practices, irrigation, soil water conservation measures

| rowspan="10"| Economic and financial outcomes

| Farming households that adapted produced about 33% more rice than households that did not adapt after controlling for all heterogeneity.

| [[#Khanal--2018a|Khanal et al. (2018a)]]

|-
| Increased rainfall variability in India

| Farmer’s training on agronomic measures, for example, alternate drying and wetting (ADW), modified system of rice intensification (MSRI) and direct-seeded rice (DSR)

| The capacity building and water saving increased crop yields by 960 kg ha –1 , 930 kg ha –1 and 770 kg kg –1 through the adoption of AWD, MSRI and DSR, respectively. The three practices have increased farmers’ income and decreased the cost of cultivation by up to USD 169 ha –1 .

| [[#Kakumanu--2019|Kakumanu et al. (2019)]]

|-
| Droughts and changes in the seasonality of rainfall in Pakistan

| Adjusting sowing time of wheat

| Household income and wheat yields were higher for households who adjusted the sowing time to cope with climate risks than those who did not, after controlling for other factors.

| [[#Rahut--2017|Rahut and Ali (2017)]]

|-
| Droughts in North China Plains

| Irrigation

| Adding one extra irrigation could increase wheat yield by up to 12.8% in a severe drought year.

| [[#Wang--2019a|Wang et al. (2019a)]]

|-
| Soil degradation; extreme rainfall events and high runoff causing erosion in Mali

| Soil and water conservation using contour ridges and improved millet and sorghum cultivars

| Millet grain yield during 2012–2014 was statistically higher in contour ridge terrace plots than the control, with yield differences ranging from 301 kg ha –1 in 2012 to 622 kg ha –1 in 2013. Improved varieties produced on average 55% more yield than the local ones.

| [[#Traore--2017|Traore et al. (2017)]]

|-
| Drought, floods, hailstorm and erratic rainfall, Ethiopia

| On-farm agricultural water management

| The net revenue from adopting a combination of agricultural water management and modern seeds or inorganic fertiliser is significantly higher by 7600 and 1500 Birr ha –1 , respectively, than adopting modern seeds or inorganic fertiliser alone. Birr is the Ethiopian currency.

| [[#Teklewold--2017|Teklewold et al. (2017)]]

|-
| Droughts and general climate impacts, South Africa

| Crop insurance and irrigation

| Farmers who insured their farm business and had access to irrigation had relatively higher net revenue than those who did not, but this link is not causal. Instead, it shows causality could go either way, including those farmers who were better off getting their business insured.

| Elum et al. (2018)

|-
| Droughts and floods in Kenya

| Migration

| Remittance income enables uptake of costlier adaptation measures such as a change in livestock species, which also have higher returns for households. Therefore, the study was not causal in its inference.

| [[#Ng’ang’a--2016|Ng’ang’a et al. (2016)]]

|-
| Droughts in Nigeria

| Drought-tolerant varieties

| Per capita, food expenditure of those who adopted drought-tolerant maize was significantly lower than those who did not after controlling for everything else and causal inference.

| [[#Wossen--2017|Wossen et al. (2017)]]

|-
| General climate impacts, including rainfall variability in Brazil

| Agroforestry systems as land use in rural municipalities

| The land value in the municipalities with agroforestry was higher than that of the municipalities where the agroforestry scheme was not implemented.

| [[#Schembergue--2017|Schembergue et al. (2017)]]

|-
| Water quality deterioration due to floods in Bangladesh

| Water, sanitation and health WaSH programme

| rowspan="5"| Outcomes for vulnerable people

| Children: prevalence of childhood diarrhoea reduced by 35% in midline prevalence, 8.9% and by 73% in end line prevalence, 3.6% compared to baseline prevalence 13.7%.. Inferences are causal.

| [[#Dey--2019|Dey et al. (2019)]]

|-
| Droughts in Zimbabwe

| Adoption of drought-tolerant maize varieties by smallholder farmers

| Smallholder farmers: Smallholder farmers practising conservation agriculture (CA) were as likely to adopt drought-tolerant maize varieties as other farmers and thus benefit from increased yields and incomes.

| [[#Makate--2019|Makate et al. (2019)]]

|-
| General climate impacts, including droughts in Niger

| Crop diversification

| Poor households: Crop diversification mainly benefits the most vulnerable households; the impact on the poorest group ranges from double to triple the impact on the wealthiest group.

| Asfaw et al. (2018)

|-
| Droughts and general climate impacts in Malawi and Zimbabwe

| Conservation agriculture; drought-tolerant maize and improved legume varieties

| Female farmers: Yield and income effects on the adoption of conservation agriculture and improved varieties of maize and legumes were both positive for men and women.

| [[#Makate--2019|Makate et al. (2019)]]

|-
| Historically widespread and severe droughts in Ethiopia in 1999, 2002, 2003, 2005 and 2008.

| Government safety net programme called Productive Safety Net Programme (PSNP)

| Poor households: PSNP transfers reduce chronic poverty level from 15.7% to 10.6% and increase the never poor share from 11.5% to 15.8%.

| [[#Gao--2018|Gao and Mills (2018)]]

|-
| Droughts in

Kenya

| Water harvesting structures, for example, sand dams

| rowspan="4"| Water-related outcomes

| Sand dams increase groundwater storage in riverbanks by up to 40%, which is maintained throughout the year.

| [[#Ryan--2016|Ryan and Elsner (2016)]]

|-
| Millennium drought in Australia

| Water trading

| Irrigation application rates fell in the dairy industry from 4.2 million litres ha –1 in 2000–2001 to 3.5 million litres ha –1 in 2005–2006

| [[#Kirby--2014|Kirby et al. (2014)]]

|-
| Droughts, floods and soil erosion and sediment load in a river basin in France

| Agreement signed between water and electricity utilities and farmers

| Agreement between water and electricity utilities to compensate farmers for reducing water use resulted in a decrease in water demand from 310 Mm 3 in 1997 to 220 Mm 3 in 2012 in the Durance Valley irrigation system in France.

| [[#Andrew--2017|Andrew and Sauquet (2017)]]

|-
| Drought in India

| The reducing area under irrigated rice crop

| Reduced rice irrigation resulted in over 60 mm ha –1 of water savings compared to irrigated rice crops on that land.

| [[#Hochman--2017b|Hochman et al. (2017b)]]

|-
| Floods due to cyclonic storms and tidal inundation in Bangladesh

| Planting of vetiver grass for stabilising coastal embankments

| rowspan="3"| Ecological and environmental outcomes

| Households that planted vetiver grass around their homestead and nearby road managed to save their houses and assets from the recent cyclonic storm and tidal inundation.

| Barua et al. (2017)

|-
| General climate impacts, including rainfall variability in Brazil

| Agroforestry systems as land use in rural municipalities

| Trees planted as a part of the agroforestry programme provide thermal comfort to both animals and humans.

| [[#Schembergue--2017|Schembergue et al. (2017)]]

|-
| Drought in 2015 in Ethiopia

| Contour ridge terraces as soil water conservation measure

| Contour ridge terraces primarily controlled water runoff and soil erosion and acted as a buffer during the 2015 Ethiopian drought.

| [[#Kosmowski--2018|Kosmowski (2018)]]

|-
| Drought and rainfall variability in Pakistan

| Climate-smart agricultural practices

| rowspan="3"| Institutional and sociocultural outcomes

| Farmers who adopted climate-smart practices also tended to form a better relationship with local extension agents and reached out to them more frequently. Again, however, causality might as well lie the other way round.

| [[#Imran--2019|Imran et al. (2019)]]

|-
| Droughts, Mexico

| Strengthening of local water users’ associations through external assistance programmes

| Local water user’s associations were able to reduce water abstractions during years of severe droughts.

| [[#Villamayor-Tomas--2017|Villamayor-Tomas and García-López (2017)]]

|-
| Rainfall variability in Niger

| Community-based adaptation and through adaptation learning programmes

| More robust social networks where women were able to take important decisions

| [[#Vardakoulias--2015|Vardakoulias and Nicholles (2015)]]

|}

Droughts, followed by precipitation variability and extreme precipitation, are the two most common hazards against which adaptation responses are forged. The other three top hazards are general climate impacts, heat-related hazards and inland and riverine flooding (Figure 4.25). The majority of the adaptation responses across all categories were introduced by individuals and households, followed by the civil society, and hence autonomous (Figure 4.26). The private sector (defined as profit-making companies and distinct from individual farmers and households) has played a relatively minor role in initiating adaptation responses. However, the low participation of the private sector in initiating adaptation responses could be partly an artefact of the nature of documentation.

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[[File:47fa182350f4d34e352a3fb66f9d0911 IPCC_AR6_WGII_Figure_4_025.png]]

'''Figure 4.25 |''' '''Water-related adaptations and climate hazards against which adaptation responses are forged.''' Evidence and confidence are derived in the same way as in Figure 4.23.

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[[File:f4536d09789b8e31d9247a0d3ab2feb3 IPCC_AR6_WGII_Figure_4_026.png]]

'''Figure 4.26 |''' '''Water-related adaptations and their initiators.''' The initiator of adaptation is defined broadly and includes the entities who initiate a response, implement that response or engage in that response in any way, including leading, financing or enabling. Evidence and confidence are derived in the same way as in Figure 4.23.

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==== 4.7.1.2 Benefits, Including Co-benefits of Water-related Adaptation Responses and Resulting Maladaptation ====

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There is no consensus in the literature about ways of measuring the effectiveness of current adaptation responses in reducing climate-related impacts ( [[#Singh--2021|Singh et al., 2021]] ). However, various methodologies, including feasibility assessment, have been deployed ( [[#Williams--2021|Williams et al., 2021]] ). Given the methodological challenges in defining and measuring the effectiveness of adaptation in reducing climate risks, in this section, we focus on outcomes of water-related adaptation across several dimensions. A total of 359 studies were identified to contain sufficiently ''robust evidence'' of documented adaptation outcomes to form the basis of this assessment (SM4.2, Table SM4.5; [[#Berrang-Ford--2021a|Berrang-Ford et al., 2021a]] ; [[#Mukherji--2021|Mukherji et al., 2021]] ). Positive outcomes denote benefits of adaptation, while negative outcomes may mean that adaptation was not effective in bringing any benefits or that it was maladaptive ( [[#Schipper--2020|Schipper, 2020]] ).

We assess outcomes across five indicators: (a) economic and financial indicators, such as improvements in crop yields and resulting incomes; increase in profits, higher savings or lesser losses from hazards; (b) impacts on vulnerable people, for example, on women, children and Indigenous Peoples; (c) water-related impacts, for example, improved water use efficiency, water saving, reduction in water withdrawals and application; (d) ecological and environmental impacts such as lesser energy use, better soil structures and better thermal comfort.; (e) institutional and sociocultural impacts such as improved social capital and stronger communities of practice, equity; and strengthening of local institutions or national policies. Of these 359 studies, 319 documented beneficial outcomes across one or more indicators, while the remaining 40 presented no beneficial outcomes. Illustrative examples are shown in Table 4.9, while the distribution of these responses with positive outcomes is shown in Figure 4.27, and indicates that economic benefits of adaptation are more common in developing countries, while benefits along ecological dimensions are more common in the developed countries,

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[[File:2518c328ae4e704d76634c50e1050e2f IPCC_AR6_WGII_Figure_4_027.png]]

'''Figure 4.27 |''' '''Top panel: location of case studies of water-related adaptation responses (996 data points from 319 studies).''' In these 996 data points, at least one positive outcome was recorded in one of the five outcome indicators. These outcome indicators are economic/financial, outcomes for vulnerable people, ecological/environmental, water-related, and sociocultural and institutional. Middle panel: the top six documented adaptation options per region as a fraction of the total of reported studies, with grey bars containing the share of all other adaptation responses. In most instances, the top six adaptation categories include nearly 3/4 of the studies. Bottom panel: The spider diagrams show the number of studies reporting beneficial outcomes for one or more dimensions for the top six adaptation options identified in each region. Due to a small number of studies in small island states, a spider diagram was not generated for the small island states.

Co-benefits are defined as mitigation benefits resulting from an adaptation response ( [[#Deng--2017|Deng et al., 2017]] ). Around a quarter of papers that documented positive adaptation outcomes also reported mitigation co-benefits. Agroforestry, community forests and forest-based adaptations are the most oft-cited examples of mitigation co-benefits ( [[#Bhatta--2015|Bhatta et al., 2015]] ; [[#Etongo--2015|Etongo et al., 2015]] ; [[#Weston--2015|Weston et al., 2015]] ; [[#Pandey--2017|Pandey et al., 2017]] ; [[#Sain--2017|Sain et al., 2017]] ; [[#Sánchez--2017|Sánchez and Izzo, 2017]] ; [[#Wood--2017|Wood et al., 2017]] ; [[#Adhikari--2018a|Adhikari et al., 2018a]] ; [[#Hellin--2018|Hellin et al., 2018]] ; [[#Aniah--2019|Aniah et al., 2019]] ; [[#Quandt--2019|Quandt et al., 2019]] ; also see Box 5.11). Other examples include mitigation benefits of climate-smart agricultural practices that reduce input intensity and help in carbon sequestration ( [[#Arslan--2015|Arslan et al., 2015]] ; [[#Somanje--2017|Somanje et al., 2017]] ), retrofitting buildings in urban areas with energy-efficient devices for lowering electricity bills and emissions ( [[#Fitzgerald--2016|Fitzgerald and Lenhart, 2016]] ) and reuse of treated wastewater for irrigation and urban uses ( [[#Morote--2019|Morote et al., 2019]] ) (Box 4.5, 4.7.6).

Not all adaptation responses reduce risks, and some may have long-term maladaptive outcomes, even if they are beneficial in the short term. Maladaptation often stems from poor planning and implementation of adaptation responses and because of not addressing the root causes of vulnerability ( [[#Schipper--2020|Schipper, 2020]] ; [[#Eriksen--2021|Eriksen et al., 2021]] ). Of the 319 case studies where adaptation response was found to have some beneficial outcomes, around one third of them also mentioned the possibility of maladaptation. Migration can often have maladaptive outcomes because migration can exacerbate the inherent vulnerabilities of migrants ( [[#4.6.8|Section 4.6.8]] ). For example, slum dwellers in cities may earn higher incomes, but their quality of life worsens ( [[#Ayeb-Karlsson--2016|Ayeb-Karlsson et al., 2016]] ). In some instances, even wage rates in migration hotspots can remain low due to the high volume of the migrant population ( [[#Fenton--2017b|Fenton et al., 2017b]] ); as such, it does not help buffer consumption against rainfall shocks ( [[#Gao--2018|Gao and Mills, 2018]] ). Migration also has gendered impacts, with girls from migrating families being taken out of school ( [[#Gioli--2014|Gioli et al., 2014]] ) or interrupting children’s education overall ( [[#Warner--2014|Warner and Afifi, 2014]] ). In planned relocation from vulnerable urban slums, relocation sites can be far from job sites and increase social conflicts ( [[#Tauhid--2018|Tauhid and Zawani, 2018]] ).

Adaptation responses that focus on improving incomes through production intensification can have maladaptive outcomes. An oft-cited example of this is groundwater overuse as a result of irrigation intensification. There is widespread evidence of groundwater overuse in many countries in Africa ( [[#Mapfumo--2017|Mapfumo et al., 2017]] ), in the Middle East and North Africa ( [[#Petit--2017|Petit et al., 2017]] ; [[#Daly-Hassen--2019|Daly-Hassen et al., 2019]] ), in Asia ( [[#Burchfield--2016|Burchfield and Gilligan, 2016]] ; [[#Zhang--2016b|]] [[#Zhang--2016|Zhang et al., 2016]] b ; [[#Kattumuri--2017|Kattumuri et al., 2017]] ), in Spain ( [[#Petit--2017|Petit et al., 2017]] ) and in Australia ( [[#Kirby--2014|Kirby et al., 2014]] ) (Sections 4.2.6, 4.6.2, Box 4.3). Intensification-based approaches also increase costs of cultivation ( [[#Mussetta--2016|Mussetta et al., 2016]] ; [[#Wang--2018|Wang and Chen, 2018]] ; [[#Quan--2019|Quan et al., 2019]] ), and can lead to more use of fertilisers and herbicides ( [[#Thierfelder--2015|Thierfelder et al., 2015]] ; [[#Sujakhu--2016|Sujakhu et al., 2016]] ; [[#Khanal--2018a|Khanal et al., 2018a]] ; [[#Yamba--2019|Yamba et al., 2019]] ). Diversification away from food crops can also compromise domestic food security ( [[#Kloos--2014|Kloos and Renaud, 2014]] ; [[#Brüssow--2017|Brüssow et al., 2017]] ).

Even interventions that have positive carbon co-benefits like forestry and agroforestry can have maladaptive consequences on land and water resources, especially if inappropriate species ( [[#Etongo--2015|Etongo et al., 2015]] ) with higher water demands are grown ( [[#Krishnamurthy--2019|Krishnamurthy et al., 2019]] ) ( [[#4.7.6|Section 4.7.6]] ).

In summary, current adaptation responses have benefits across several dimensions. In developing countries, most adaptation measures improve economic outcomes ( ''high confidence'' ). Adaptation responses also have benefits in terms of water outcomes and environmental and ecological parameters, and these benefits are more commonly manifested in developed countries ( ''high confidence'' ). Of the papers assessed for water-related adaptation, roughly one fourth reported adaptation co-benefits ( ''high confidence'' ). In contrast, one third of studies reported maladaptive outcomes, now or in the future ( ''high confidence'' ), emphasizing the importance of looking at synergies and trade-offs. Despite many adaptation case studies, there is a knowledge gap in understanding if the benefits of adaptation also translate into a reduction of climate impacts, and if so, to what extent, and under what conditions ( ''high confidence'' ). In view of this critical knowledge gap, our assessment is limited to benefits of current adaptation responses.

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