Evaluation of water loss in transit and surface runoff in a Brazilian semi-arid basin

Abstract The objective of this work was to propose and evaluate a model to estimate transit water losses and surface runoff in a Brazilian semi-arid basin, fundamental components in the hydrological studies of the region, such as in the verification of hydrological connectivity. The study area was the Orós Reservoir Basin, located in the state of Ceará. The modeling of transit water loss and surface runoff were developed based on the work of Araújo and Ribeiro (1996) and Peter et al. (2014). In the proposed model, the parameter of loss in transit (k) was estimated at 0.027 km-1 for a section of the river basin, and when simulated for other stretches it provided good flow results at the end of the stretch, obtaining an NSE of 82%. The value of the runoff coefficient was estimated at 3% and when evaluating a spatial variation of this coefficient in the basin, the values varied from 2% to 12%, and the use of specialized runoff coefficient (RC) values promoted a higher NSE in the discharge simulation in the basin. It is concluded that the proposed model to estimate transit water losses and surface runoff demonstrated a high efficiency in the simulation of hydrological processes. The basin of Orós reservoir presented a high variability of the coefficient of surface runoff, justifying the need for a greater spatiality of this coefficient in heterogeneous environments.

摘要
本研究旨在提出并评估一款模型，用于估算巴西半干旱流域的输水损失与地表径流——二者均为该区域水文研究（如水文连通性验证）的核心组成要素。本次研究的区域为位于巴西塞阿拉州（Ceará）的奥罗斯水库流域（Orós Reservoir Basin）。输水损失与地表径流的建模工作基于Araújo与Ribeiro（1996）以及Peter等（2014）的研究成果。在本研究提出的模型中，针对某一河段的输水损失参数（k）被估算为0.027 km⁻¹；将该参数应用于其他河段进行模拟时，在河段末端获得了较好的流量模拟效果，纳什效率系数（Nash-Sutcliffe Efficiency，NSE）达82%。径流系数（runoff coefficient, RC）的基准估算值为3%；在对该流域内该系数的空间变异开展评估时，其取值范围为2%至12%；采用专属径流系数（RC）值可提升流域径流模拟的纳什效率系数。研究结论显示，本研究提出的输水损失与地表径流估算模型在水文过程模拟中展现出较高的效率。奥罗斯水库流域的地表径流系数存在较高变异性，这说明在非均质环境下，有必要对该系数开展更精细化的空间表征。