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

Abstract

Decentralized rainwater harvesting (RWH) is a promising approach to mitigate drought in the drylands. However, an insufficient understanding of its impact on hydrological processes has resulted in poor resource planning in this area. This study is a meta-analysis of 25 agricultural watersheds representing a range of rainfall and soil types in the semi-arid tropics. Rainfall-runoff-soil loss relationship was calculated at daily, monthly and yearly levels, and the impact of RWH interventions on surface runoff and soil loss was quantified. A linear relationship was observed between daily rainfall and surface runoff up to 120 mm of rainfall intensity, which subsequently saw an exponential increase. About 200–300 mm of cumulative rainfall is the threshold to initiate surface runoff in the Indian semi-arid tropics. Rainwater harvesting was effective in terms of enhancing groundwater availability (2.6–6.9 m), crop intensification (40–100%) and farmers’ incomes (50–200%) in different benchmark watersheds. An average of 40 mm of surface runoff was harvested annually and it reduced soil loss by 70% (3 ton/ha/year compared to 1 ton/ha/year in non-intervention stage. The study further quantified runoff at 25th, 50th and 75th percentiles, and found that more than 70% of the area in the Indian semi-arid tropics has high to medium potential for implementing RWH interventions.

Improving Spatial Resolution in Soil and Drainage Data to Combine Natural and Anthropogenic Water Functions at Catchment Scale in Agricultural Landscapes

“…Trends in the current climate indicate more extreme rainfall events (e.g., Grusson et al, 2021), and the synergetic effects of multiple weather events (so-called compound events) call for improved knowledge of landscape responses to various events and their interactions at local scale (Zscheischler et al, 2018). The change of pulse events will require new approaches in data collection and hydrological modelling; moreover, complementary studies at various scales are needed to understand the impacts and, e.g., design of mitigation measures (e.g., Garg et al, 2022). Furthermore, although data might be available at high spatial resolution, the temporal scale of input parameters for modelling short-term events might be too coarse to match the means, an issue to discuss, e.g., when linking landscape hydrology with short-term weather events.…”

Scaling Up Indigenous Rainwater Harvesting: A Preliminary Assessment in Rajasthan, India

“…The Inverse Distance Weight (IDW) interpolation technique was employed to estimate rainfall in areas without direct measurements. Researchers [46] reported that a mean annual rainfall of 150-750 mm/year was suitable for most RWH techniques to be effective, and [47] reported that a cumulative annual rainfall of 200-300 mm in the Indian semi-arid tropics was necessary to initiate surface runoff for rainwater storage. Based on these findings, annual rainfall in the study area was classified into three categories, including a low range with minimum significance for RWH structures < 400 mm ranked '1', medium annual rainfall range 400-700 mm assigned '2', and rainfall > 700 mm ranked '3'.…”

Sustainable education and youth confidence as pillars of future civil society

“…Amidst ongoing unsettling events, including a global pandemic and a war in Ukraine, the challenge of sustainability remains central 1 , 2 . In addition, there are many problems related to health, human rights and the environment, including malnutrition and food insecurity 3 , as well as water shortage 4 , 5 . The Sustainable Development Goals (SDGs) offer a pathway to reconciling economic growth with environmental concerns, through a highly interconnected framework of analysis 6 .…”