Editing IPCC:AR6/SRCCL/Chapter-3 (section)

=== 3.7.5 Integrated watershed management ===

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Desertification has resulted in significant loss of ecosystem processes and services, as described in detail in this chapter. The techniques and processes to restore degraded watersheds are not linear and integrated watershed management (IWM) must address physical, biological and social approaches to achieve SLM objectives (German et al. 2007 <sup>[[#fn:r1726|1726]]</sup> ).

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==== 3.7.5.1 Jordan ====

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Population growth, migration into Jordan and changes in climate have resulted in desertification of the Jordan Badia region. The Badia region covers more than 80% of the country’s area and receives less than 200 mm of rainfall per year, with some areas receiving less than 100 mm (Al-Tabini et al. 2012 <sup>[[#fn:r1727|1727]]</sup> ). Climate analysis has indicated a generally increasing dryness over the West Asia and Middle East region (AlSarmi and Washington 2011 <sup>[[#fn:r1728|1728]]</sup> ; Tanarhte et al. 2015 <sup>[[#fn:r1729|1729]]</sup> ), with reduction in average annual rainfall in Jordan’s Badia area (De Pauw et al. 2015 <sup>[[#fn:r1730|1730]]</sup> ). The incidence of extreme rainfall events has not declined over the region. Locally increased incidence of extreme events over the Mediterranean region has been proposed (Giannakopoulos et al. 2009 <sup>[[#fn:r1731|1731]]</sup> ).

The practice of intensive and localised livestock herding, in combination with deep ploughing and unproductive barley agriculture, are the main drivers of severe land degradation and depletion of the rangeland natural resources. This affected both the quantity and the diversity of vegetation as native plants with a high nutrition value were replaced with invasive species with low palatability and nutritional content (Abu-Zanat et al. 2004 <sup>[[#fn:r1732|1732]]</sup> ). The sparsely covered and crusted soils in Jordan’s Badia area have a low rainfall interception and infiltration rate, which leads to increased surface runoff and subsequent erosion and gullying, speeding up the drainage of rainwater from the watersheds, which can result in downstream flooding in Amman, Jordan (Oweis 2017 <sup>[[#fn:r1733|1733]]</sup> ).

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<span id="figure-3.17a"></span>
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'''Figure 3.17a'''

<span id="anewly-prepared-micro-water-harvesting-catchment-using-the-vallerani-system."></span>
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'''(a)Newly prepared micro water harvesting catchment, using the Vallerani system.'''
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[[File:1fb888a1be66840d4733d4e59b7d5d71 Figure-3.17a-e1575973543995-1024x576.jpg]]

(a)Newly prepared micro water harvesting catchment, using the Vallerani system.

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<span id="figure-3.17b"></span>
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'''Figure-3.17b'''

<span id="b-aerial-imaging-showing-micro-water-harvesting-catchment-treatment-after-planting"></span>
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'''(b) Aerial imaging showing micro water harvesting catchment treatment after planting'''
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[[File:c46f91b0be56e92c0e20ab15e4538313 Figure-3.17b-1024x768.jpg]]

(b) Aerial imaging showing micro water harvesting catchment treatment after planting

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<span id="figure-3.17c"></span>
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'''Figure 3.17c'''

<span id="c-one-year-after-treatment.-source-stefan-strohmeier."></span>
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'''(c) one year after treatment. Source: Stefan Strohmeier.'''
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[[File:d5aac8ae1c063d1b3f3770d241841a5a Figure-3.17c.jpg]]

(c) one year after treatment. Source: Stefan Strohmeier.

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<span id="figure-3.18"></span>
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'''Figure 3.18'''

<span id="illustration-of-enhanced-soil-water-retention-in-the-mechanized-micro-rainwater-harvesting-compared-to-untreated-badia-rangelands-in-jordan-showing-precipitation-pcp-sustained-stress-level-resulting-in-decreased-production-field-capacity-and-wilting-point-for-available-soil-moisture-and-then-measured-soil-moisture-content-between-the-two-treatments-degraded-rangeland-and-the-restored-rangeland-with"></span>
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'''Illustration of enhanced soil water retention in the Mechanized Micro Rainwater Harvesting compared to untreated Badia rangelands in Jordan, showing precipitation (PCP), sustained stress level resulting in decreased production, field capacity and wilting point for available soil moisture, and then measured soil moisture content between the two treatments (degraded rangeland and the restored rangeland with […]'''
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[[File:5855d365bf8274031e1d2d6a42eef563 Figure-3.18-1024x604.jpg]]

Illustration of enhanced soil water retention in the Mechanized Micro Rainwater Harvesting compared to untreated Badia rangelands in Jordan, showing precipitation (PCP), sustained stress level resulting in decreased production, field capacity and wilting point for available soil moisture, and then measured soil moisture content between the two treatments (degraded rangeland and the restored rangeland with the Vallerani plough).

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To restore the desertified Badia an IWM plan was developed using hillslope-implemented water harvesting micro catchments as a targeted restoration approach (Tabieh et al. 2015 <sup>[[#fn:r1734|1734]]</sup> ). Mechanized Micro Rainwater Harvesting (MIRWH) technology using the ‘Vallerani plough’ (Antinori and Vallerani 1994 <sup>[[#fn:r1735|1735]]</sup> ; Gammoh and Oweis 2011 <sup>[[#fn:r1736|1736]]</sup> ; Ngigi 2003 <sup>[[#fn:r1737|1737]]</sup> ) is being widely applied for rehabilitation of highly degraded rangeland areas in Jordan. A tractor digs out small water harvesting pits on the contour of the slope (Figure 3.17) allowing the retention, infiltration and local storage of surface runoff in the soil (Oweis 2017 <sup>[[#fn:r1739|1739]]</sup> ). The micro catchments are planted with native shrub seedlings, such as saltbush ( ''Atriplex halimus'' ), with enhanced survival as a function of increased soil moisture (Figure 3.18) and increased dry matter yields (&gt;300 kg ha <sup>–1</sup> ) that can serve as forage for livestock (Oweis 2017 <sup>[[#fn:r1738|1738]]</sup> ; Tabieh et al. 2015 <sup>[[#fn:r1740|1740]]</sup> ).

Simultaneously to MIRWH upland measures, the gully erosion is being treated through intermittent stone plug intervention (Figure 3.19), stabilising the gully beds, increasing soil moisture in proximity of the plugs, dissipating the surface runoff’s energy, and mitigating further back-cutting erosion and quick drainage of water. Eventually, the treated gully areas silt up and dense vegetation cover can re-establish. In addition, grazing management practices are implemented to increase the longevity of the treatment. Ultimately, the recruitment processes and re-vegetation shall control the watershed’s hydrological regime through rainfall interception, surface runoff deceleration and filtration, combined with the less erodible and enhanced infiltration characteristics of the rehabilitated soils.

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<span id="figure-3.19a"></span>
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'''Figure 3.19a'''

<span id="a-gully-plug-development-in-september-2017."></span>
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'''(a) Gully plug development in September 2017.'''
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[[File:f605e0a6fd89abf71f911bc3d3618186 Figure-3.19a.jpg]]

(a) Gully plug development in September 2017.

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'''Figure 3.19b'''

<span id="b-post-rainfall-event-march-2018.-near-amman-jordan.-source-stefan-strohmeier."></span>
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'''(b) Post-rainfall event (March 2018). Near Amman, Jordan. Source: Stefan Strohmeier.'''
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[[File:db037d1c28a821352a091a6f25dd9046 Figure-3.19b.jpg]]

(b) Post-rainfall event (March 2018). Near Amman, Jordan. Source: Stefan Strohmeier.

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In-depth understanding of the Badia’s rangeland status transition, coupled with sustainable rangeland management, are still subject to further investigation, development and adoption; a combination of all three is required to mitigate the ongoing degradation of the Middle Eastern rangeland ecosystems.

Oweis (2017) <sup>[[#fn:r1813|1813]]</sup> indicated that the cost of the fully automated Vallerani technique was approximately 32 USD ha-1. The total cost of the restoration package included the production, planting and maintenance of the shrub seedlings (11 USD ha <sup>–1)</sup> . Tabieh et al. (2015) <sup>[[#fn:r1812|1812]]</sup> calculated a benefit-cost ratio (BCR) of above 1.5 for re-vegetation of degraded Badia areas through MIRWH and saltbush. However, costs vary based on the seedling’s costs and availability of trained labour.

Water harvesting is not a recent scientific advancement. Water harvesting is known to have been developed during the Bronze Age and was widely practiced in the Negev Desert during the Byzantine time period (1300–1600 years ago) (Fried et al. 2018 <sup>[[#fn:r1741|1741]]</sup> ; Stavi et al. 2017 <sup>[[#fn:r1742|1742]]</sup> ). Through construction of various structures made of packed clay and stone, water was either held on site in half-circular dam structures ( ''hafir)'' that faced up-slope to capture runoff, or on terraces that slowed water allowing it to infiltrate and to be stored in the soil profile. Numerous other systems were designed to capture water in below-ground cisterns to be used later to provide water to livestock or for domestic use. Other water harvesting techniques divert runoff from hillslopes or wadis and spread the water in a systematic manner across ''playas'' and the toe-slope of a hillslope. These systems allow production of crops in areas with 100 mm of average annual precipitation by harvesting an additional 300+ mm of water (Beckers et al. 2013 <sup>[[#fn:r1743|1743]]</sup> ). Water harvesting is a proven technology to mitigate or adapt to climate change where precipitation may be reduced, and allow for small-scale crop and livestock production to continue supporting local needs.

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==== 3.7.5.2 India ====

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The second great challenge after the Green Revolution in India was the low productivity in the rain-fed and semi-arid regions where land degredation and drought were serious concerns. In response to this challenge IWM projects were implemented over large areas in semi-arid biomes over the past few decades. IWM was meant to become a key factor in meeting a range of social development goals in many semi-arid rainfed agrarian landscapes in India (Bouma et al. 2007 <sup>[[#fn:r1744|1744]]</sup> ; Kerr et al. 2002 <sup>[[#fn:r1745|1745]]</sup> ). Over the years, watershed development has become the fulcrum of rural development, and has the potential to achieve the twin objectives of ecosystem restoration and livelihood assurance in the drylands of India (Joy et al. 2004).

Many reports indicate significant improvements in mitigation of drought impacts, raising crops and fodder, livestock productivity, expanding the availability of drinking water and increasing incomes as a result of IWM (Rao 2000), but in some cases overall the positive impact of the programme has been questioned and, except in a few cases, the performance has not lived up to expectations (Joy et al. 2004; JM Kerr et al. 2002). Comparisons of catchments with and without IWM projects using remotely sensed data have sometimes shown no significant enhancement of biomass, in part due to methodological challenges of space for time comparisons (Bhalla et al. 2013 <sup>[[#fn:r1746|1746]]</sup> ). The factors contributing to the successful cases were found to include effective participation of stakeholders in management (Rao 2000; Ratna Reddy et al. 2004 <sup>[[#fn:r1747|1747]]</sup> ).

Attribution of success in soil and water conservation measures was confounded by inadequate monitoring of rainfall variability and lack of catchment hydrologic indicators (Bhalla et al. 2013 <sup>[[#fn:r1748|1748]]</sup> ). Social and economic trade-offs included bias of benefits to downstream crop producers at the expense of pastoralists, women and upstream communities. This biased distribution of IWM benefits could potentially be addressed by compensation for environmental services between communities (Kerr et al. 2002 <sup>[[#fn:r1749|1749]]</sup> ). The successes in some areas also led to increased demand for water, especially groundwater, since there has been no corresponding social regulation of water use after improvement in water regime (Samuel et al. 2007 <sup>[[#fn:r1750|1750]]</sup> ). Policies and management did not ensure water allocation to sectors with the highest social and economic benefits (Batchelor et al. 2003 <sup>[[#fn:r1751|1751]]</sup> ). Limited field evidence of the positive impacts of rainwater harvesting at the local scale is available, but there are several potential negative impacts at the watershed scale (Glendenning et al. 2012 <sup>[[#fn:r1752|1752]]</sup> ). Furthermore, watershed projects are known to have led to more water scarcity, and higher expectations for irrigation water supply, further exacerbating water scarcity (Bharucha et al. 2014 <sup>[[#fn:r1753|1753]]</sup> ).

In summary, the mixed performance of IWM projects has been linked to several factors. These include: inequity in the distribution of benefits (Kerr et al. 2002); focus on institutional aspects rather than application of appropriate watershed techniques and functional aspects of watershed restoration (Joy et al. 2006; Vaidyanathan 2006 <sup>[[#fn:r1755|1755]]</sup> ); mismatch between scales of focus and those that are optimal for catchment processes (Kerr 2007 <sup>[[#fn:r1756|1756]]</sup> ); inconsistencies in criteria used to select watersheds for IWM projects (Bhalla et al. 2011 <sup>[[#fn:r1757|1757]]</sup> ); and in a few cases additional costs and inefficiencies of local non-governmental organisations (Chandrasekhar et al. 2006 <sup>[[#fn:r1758|1758]]</sup> ; Deshpande 2008 <sup>[[#fn:r1759|1759]]</sup> ). Enabling policy responses for improvement of IWM performance include: a greater emphasis on ecological restoration rather than civil engineering; sharper focus on sustainability of livelihoods than just conservation; adoption of ‘water justice’ as a normative goal and minimising externalities on non-stakeholder communities; rigorous independent biophysical monitoring, with feedback mechanisms and integration with larger schemes for food and ecological security, and maintenance of environmental flows for downstream areas (Bharucha et al. 2014 <sup>[[#fn:r1760|1760]]</sup> ; Calder et al. 2008 <sup>[[#fn:r1761|1761]]</sup> ; Joy et al. 2006). Successful adaptation of IWM to achieve land degradation neutrality would largely depend on how IWM creatively engages with dynamics of large-scale land use and hydrology under a changing climate, involvement of livelihoods and rural incomes in ecological restoration, regulation of groundwater use, and changing aspirations of rural population ( ''robust evidence, high agreement'' ) (O’Brien et al. 2004 <sup>[[#fn:r1762|1762]]</sup> ; Samuel et al. 2007 <sup>[[#fn:r1763|1763]]</sup> ; Samuel and Joy 2018 <sup>[[#fn:r1764|1764]]</sup> ).

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==== 3.7.5.3 Limpopo River Basin ====

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Covering an area of 412,938 km <sup>2</sup> , the Limpopo River basin spans parts of Botswana, South Africa, Zimbabwe and Mozambique, eventually entering into the Mozambique Channel. It has been selected as a case study as it provides a clear illustration of the combined effect of desertification and climate change, and why IWM may be a crucial component of reducing exposure to climate change. It is predominantly a semi-arid area with an average annual rainfall of 400 mm (Mosase and Ahiablame 2018 <sup>[[#fn:r1765|1765]]</sup> ). Rainfall is both highly seasonal and variable, with the prominent impact of the El Niño/ La Niña phenomena and the Southern Oscillation leading to severe droughts (Jury 2016 <sup>[[#fn:r1766|1766]]</sup> ). It is also exposed to tropical cyclones that sweep in from the Mozambique Channel often leading to extensive casualties and the destruction of infrastructure (Christie and Hanlon 2001 <sup>[[#fn:r1767|1767]]</sup> ). Furthermore, there is good agreement across climate models that the region is going to become warmer and drier, with a change in the frequency of floods and droughts (Engelbrecht et al. 2011 <sup>[[#fn:r1768|1768]]</sup> ; Zhu and Ringler 2012). Seasonality is predicted to increase, which in turn may increase the frequency of flood events in an area that is already susceptible to flooding (Spaliviero et al. 2014 <sup>[[#fn:r1769|1769]]</sup> ).

A clear need exists to both address exposure to flood events as well as predicted decreases in water availability, which are already acute. Without the additional impact of climate change, the basin is rapidly reaching a point where all available water has been allocated to users (Kahinda et al. 2016 <sup>[[#fn:r1770|1770]]</sup> ; Zhu and Ringler 2012). The urgency of the situation was identified several decades ago (FAO 2004), with the countries of the basin recognising that responses are required at several levels, both in terms of system governance and the need to address land degradation.

Recent reviews of the governance and implementation of IWM within the basin recognise that an integrated approach is needed and that a robust institutional, legal, political, operational, technical and support environment is crucial (Alba et al. 2016 <sup>[[#fn:r1771|1771]]</sup> ; Gbetibouo et al. 2010 <sup>[[#fn:r1773|1773]]</sup> ; Machethe et al. 2004 <sup>[[#fn:r1774|1774]]</sup> ; Spaliviero et al. 2011 <sup>[[#fn:r1775|1775]]</sup> ; van der Zaag and Savenije 1999 <sup>[[#fn:r1776|1776]]</sup> ). Within the scope of emerging lessons, two principal ones emerge. The first is capacity and resource constraints at most levels. Limited capacity within Limpopo Watercourse Commission (LIMCOM) and national water management authorities constrains the implementation of IWM planning processes (Kahinda et al. 2016 <sup>[[#fn:r1777|1777]]</sup> ; Spaliviero et al. 2011 <sup>[[#fn:r1778|1778]]</sup> ). Whereas strategy development is often relatively well-funded and resourced through donor funding, long-term implementation is often limited due to competing priorities. The second is adequate representation of all parties in the process in order to address existing inequalities and ensure full integration of water management. For example, within Mozambique, significant strides have been made towards the decentralisation of river basin governance and IWM. Despite good progress, Alba et al. (2016) found that the newly implemented system may enforce existing inequalities as not all stakeholders, particularly smallholder farmers, are adequately represented in emerging water management structures and are often inhibited by financial and institutional constraints. Recognising economic and socio-political inequalities, and explicitly considering them to ensure the representation of all participants, can increase the chances of successful IWM implementation.

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