Yu Weiyu, Wanza Peggy, Kwoba Emmah, Mwangi Thumbi, Okotto-Okotto Joseph, Trajano Gomes da Silva Diogo, Wright Jim A
School of Ecological Technology and Engineering, Shanghai Institute of Technology, Fengxian campus, Shanghai, 201418 China.
School of Geography and Environmental Science, University of Southampton, Building 44, Highfield campus, Southampton, SO17 1BJ UK.
NPJ Clean Water. 2023;6(1):32. doi: 10.1038/s41545-023-00247-9. Epub 2023 Apr 13.
Rainwater harvesting reliability, the proportion of days annually when rainwater demand is fully met, is challenging to estimate from cross-sectional household surveys that underpin international monitoring. This study investigated the use of a modelling approach that integrates household surveys with gridded precipitation data to evaluate rainwater harvesting reliability, using two local-scale household surveys in rural Siaya County, Kenya as an illustrative case study. We interviewed 234 households, administering a standard questionnaire that also identified the source of household stored drinking water. Logistic mixed effects models estimated stored rainwater availability from household and climatological variables, with random effects accounting for unobserved heterogeneity. Household rainwater availability was significantly associated with seasonality, storage capacity, and access to alternative improved water sources. Most households (95.1%) that consumed rainwater faced insufficient supply of rainwater available for potable needs throughout the year, with intermittencies during the short rains for most households with alternative improved sources. Although not significant, stored rainwater lasts longer for households whose only improved water source was rainwater (301.8 ± 40.2 days) compared to those having multiple improved sources (144.4 ± 63.7 days). Such modelling analysis could enable rainwater harvesting reliability estimation, and thereby national/international monitoring and targeted follow-up fieldwork to support rainwater harvesting.
雨水收集可靠性，即每年雨水需求得到完全满足的天数比例，很难从作为国际监测基础的横断面住户调查中估算出来。本研究调查了一种建模方法的应用，该方法将住户调查与网格化降水数据相结合，以评估雨水收集可靠性，并以肯尼亚锡亚亚县农村地区的两项地方规模住户调查为例进行说明。我们采访了234户家庭，发放了一份标准问卷，该问卷还确定了家庭储存饮用水的来源。逻辑混合效应模型根据家庭和气候变量估计储存雨水的可获得性，随机效应考虑了未观察到的异质性。家庭雨水可获得性与季节性、储存能力以及获得其他改良水源的机会显著相关。大多数使用雨水的家庭（95.1%）全年面临可供饮用的雨水供应不足的问题，对于大多数有其他改良水源的家庭来说，短雨期间会出现间歇性缺水。虽然不显著，但与有多种改良水源的家庭（144.4±63.7天）相比，唯一的改良水源是雨水的家庭储存的雨水持续时间更长（301.8±40.2天）。这种建模分析可以实现雨水收集可靠性的估算，从而进行国家/国际监测以及有针对性的后续实地调查，以支持雨水收集工作。
