Impact of Rainwater Harvesting on Hydrological Processes in a Fragile Watershed of South Asia

Abstract

Agricultural water management (AWM) interventions play an important role in ensuring sustainable food production and mitigating climate risks. This study was carried out in a watershed located in a low rainfall (400-600 mm) region of western India. The Soil and Water Assessment Tool model was calibrated using surface runoff, soil loss, and reservoir storage levels, between the year 2000 and 2006. The investigation indicated that the various AWM interventions increased groundwater recharge from 30 mm/year to 80 mm/year and reduced surface runoff from 250 mm/year to 100 mm/year. The intervention structures were refilled two to three times during the monsoon season depending on rainfall intensity and duration. The interventions have the advantage of building a resilient system by enhancing groundwater availability even in dry years, stimulating crop intensification and protecting the landscape from severe erosion. The results indicate that soil erosion has been reduced by more than 75% compared to the nonintervention situation. Moreover, the AWM interventions led to the cultivation of 100-150 ha of fallow land with high-value crops (horticulture, vegetables, and fodder). Household income increased by several folds compared to the nonintervention situation. The study showed about 50% reduction in downstream water availability, which could be a major concern. However, there are a number of ecosystem trade-offs such as improved base flow to the stream and reduction in soil loss that should be considered. The study is of great importance to stakeholders to decide on the optimal design for AWM interventions to achieve sustainable development goals.

Identifying potential zones for rainwater harvesting interventions for sustainable intensification in the semi-arid tropics

“…Agricultural productivity in these watersheds before the project interventions ranged between 0.5 and 2.0 ton/ha. Nearly 30–40% of agricultural land remained fallow largely due to water scarcity 18 , 19 . More than 90% of the farmers in these watersheds owned less than 2.0 ha, were poor and endured malnutrition 18 , 19 .…”

“…Nearly 30–40% of agricultural land remained fallow largely due to water scarcity 18 , 19 . More than 90% of the farmers in these watersheds owned less than 2.0 ha, were poor and endured malnutrition 18 , 19 . Given these conditions, the watersheds were developed as sites of learning by implementing a range of in-situ conservation and ex-situ rainwater harvesting interventions at landscape and farm scales (Fig.…”

“…Earthen field bunds, retention ditches, and raised beds were the common in-situ interventions implemented mainly in the degraded uplands to enhance residual soil moisture and control land degradation 19 . A ridge-to-valley approach was followed exposing upland locations to in-situ interventions to protect the landscape from excessive erosion to enhance water retention ability through earthen structures and biological measures.…”

Impact of agricultural water management interventions on upstream–downstream trade‐offs in the upper Cauvery catchment, southern India: a modelling study*

“…A few studies have reported that check dams and various rainwater storage structures have harvested 5-10 times the total storage capacity developed in the degraded landscapes of central and western India, with rainfall ranging from 600 to 900 mm (Singh et al, 2014;Garg et al, 2021). AWM interventions enhanced groundwater recharge (by 30-50%), crop productivity (by 50-200%), crop intensification (by 30-50%) and controlled soil erosion and land degradation (by 70-90%) compared to the non-intervention stage (Garg et al, 2011(Garg et al, , 2012aSingh et al, 2014;Garg et al, 2020a;Garg et al, 2021). Garg et al (2011) modelled the impact of various AWM interventions on hydrological processes in the Osman Sagar catchment (736 km 2 ) of the Musi basin in the semi-arid tropics of southern India.…”

Transforming livestock productivity through watershed interventions: A case study of Parasai-Sindh watershed in Bundelkhand region of Central India

“…While the drylands are also beset with poverty and malnutrition largely due to fragmented land holdings, poor production and frequent crop failure (Bharucha, 2019;Chikwanha et al, 2021), they hold huge potential to bridge yield gaps through natural resource management interventions, since current resource use efficiency is much less than the achievable potential (Anantha et al, 2021a;Wani et al, 2017). Studies indicate that the conversion of degraded pasture lands into productive grasslands is not only helping meet fodder demand but also supporting other ecosystem services (Anantha et al, 2021b;Garg et al, 2021b). A meta-analysis of 86 studies revealed a higher net accumulation of soil carbon, more microbial activity, and other benefits when grasslands are converted into the silvopastoral system (Feliciano et al, 2018).…”