Sustainable provision of raw water based on the management of ecosystem services in small watersheds

Abstract The differentiated effects of the provision of environmental services in a watershed are due to the capacity of regularization of outflows in its mouth. In impacted areas, this environmental function is affected, and in some situations, it ceases to exist completely. This study characterized the soil and the production of sediments in anthropic watersheds, with the purpose of describing and evaluating the environmental services offered by a watershed undergoing anthropic transformation. The analyses show that the water flow in the remaining watersheds was preferably horizontal in the transmission zone, and these areas represent almost all areas. The values of hydraulic conductivity suggest that the infiltration decreases with soil depth; this fact is corroborated by the values of bulk density. The natural regions of water accumulation, the floodplains or outcrops zones, are small and do not have direct contact with the main floodplain present in the Guandu River Basin, making it impossible to recharge through other areas. Even so, water balance shows that the set of measures implemented ensured that the deficit water demand was supplied during the years of operation, even in times of water deficit. Likewise, the retention of solids in the settling tanks and in the drainage system prevented some 29,000 t of sediment from being carried between the years of 2012 and 2015.

摘要
流域（watershed）内环境服务（environmental services）供给的差异化效应，源于其河口处的径流调节能力。在受干扰区域，该环境服务功能会受到损害，部分情形下甚至会完全丧失。本研究针对人为（anthropic）流域的土壤特征与泥沙产出开展表征分析，旨在描述并评估正经历人为改造的流域所提供的环境服务。
分析结果表明，剩余流域内的水流在传输带中以横向流动为主，此类区域占流域总面积的绝大多数。导水率（hydraulic conductivity）的数值特征显示，土壤入渗率随土层深度增加而降低；容重（bulk density）的测定结果佐证了这一结论。
自然积水区域（即漫滩或露头带）面积狭小，且与官渡河流域（Guandu River Basin）内的主漫滩无直接连通，因此无法通过其他区域实现水量补给。即便如此，水量平衡（water balance）分析结果显示，所实施的一系列措施确保了在运营年限内，即便在缺水时段也能补足用水需求缺口。
同样，沉淀池（settling tanks）与排水系统内的固体截留作用，使得2012至2015年间约2.9万吨泥沙未被输送流失。