GR5J hydrological model code

In a river basin, the mass balance equation links total water storage (TWS), precipitation (P), actual evapotranspiration (E) and river discharge (Q). Though, a focused portion of the catchment, located between two river discharge stations, can be studied. Indeed, TWS in a downstream sub-catchment can be estimated based on the mass balance equation dTWS/dt = P + Qin - E - Qout - Qgw; where Qin, Qout, Qgw are respectively incoming river inflow, outcoming river discharge, and potential groundwater import/export in a surrounding basin. Among the different water fluxes, P, Qin and Qout can be measured, whereas actual evapotranspiration and Qgw should be estimated with a model. E and Qgw can be estimated with the lumped parameter rainfall-runoff hydrological model GR5J (Pushpalatha et al., 2011), which allow to quantify daily TWS at the scale of single hydrological basins. Here we provide a MATLAB code of the GR5J model. This model is forced with precipitation, temperature and potential evapotranspiration and computes actual river discharge. The model is based on two storage compartments - production and routing stores - which mimic the typical response of soils and groundwater to antecedent precipitation and evapotranspiration. Snow is considered and it is estimated following the method described in the HBV (Hydrologiska Byrns Vattenbalansavdelning) model (Lindstrom et al., 1997): mean catchment temperature defines both rainfall/snowfall partitioning and snow melt events. It is worth noting that GR5J does not need the specific knowledge of any intrinsic structure/property of the basin. The model is parsimonious and designed to model river discharge. Although the GR5J model is a simplified conceptual model, where only five mathematical parameters define the dynamics of the two stores and their relations, it has proven skillful in predicting river discharge better than more complex models (de Lavenne et al., 2016) and has been successfully applied to represent groundwater storage changes in Nepal rivers (Andermann et al., 2012). GR5J parameters are calibrated using a Marquard-Levenberg least squares regression analysis using root mean square error on the logarithm of observed river discharge to limit the impact of floods and promote the description of the whole water cycle.

在流域（river basin）中，水量平衡方程将总蓄水量（TWS, total water storage）、降水量（P, precipitation）、实际蒸散发量（E, actual evapotranspiration）与河道径流量（Q, river discharge）关联起来。不过，可聚焦研究两个河道径流监测站之间的子集水区。事实上，下游子流域的总蓄水量可基于水量平衡方程dTWS/dt = P + Qin - E - Qout - Qgw进行估算，其中Qin、Qout、Qgw分别代表汇入河道径流量、流出河道径流量以及周边流域的潜在地下水补给/排泄量。在各类水文通量中，降水量P、汇入径流量Qin与流出径流量Qout可直接实测，而实际蒸散发量E与地下水通量Qgw则需通过模型估算。实际蒸散发量E与地下水通量Qgw可通过集总式参数降雨-径流水文模型GR5J（Pushpalatha等，2011）进行估算，该模型可在单个水文流域尺度上量化逐日总蓄水量。本文提供了GR5J模型的MATLAB代码。该模型以降水量、气温与潜在蒸散发量作为驱动数据，计算得到实际河道径流量。模型基于两个蓄水库单元——产流库与汇流库——分别模拟土壤与地下水对前期降水及蒸散发的典型响应过程。同时考虑降雪过程，其划分与融雪规则参考HBV（Hydrologiska Byrns Vattenbalansavdelning）模型（Lindstrom等，1997）中的方法：流域平均气温决定了降雨与降雪的划分以及融雪事件的发生。值得注意的是，GR5J模型无需知晓流域的任何固有结构或属性，结构简洁，专为河道径流量模拟设计。尽管GR5J是简化的概念性水文模型，仅通过5个数学参数定义两个蓄水库的动态变化及其相互关系，但已有研究表明，其河道径流量预测效果优于诸多复杂模型（de Lavenne等，2016），且已成功应用于尼泊尔河流的地下水蓄水量变化模拟（Andermann等，2012）。GR5J模型的参数通过Marquard-Levenberg最小二乘回归分析进行率定，以观测河道径流量对数的均方根误差作为目标函数，以弱化洪水事件的影响，更全面地刻画完整水循环过程。

搜集汇总

背景与挑战

背景概述

该数据集提供了GR5J水文模型的MATLAB代码，用于估算河流流域的水量平衡，包括降水、蒸发和河流流量等参数。模型基于两个存储单元，具有参数少、计算效率高的特点，适用于单流域尺度的日水量估算。