Analysis of hydrological modelling tool for water resources management in the Valles River Basin, México

Abstract

Integrated Water Resources Management (IWRM) is a systematic process for the sustainable development, allocation and monitoring of water resources, which promotes more coordinated management of land and water, the river basin and upstream and downstream interests (UNW- DPC, 2010). As a way to approach the management of water resources in a given geographical context, it can take advantage of any available instrument or tool. Hydrological models are simplified representations of hydrological systems, and can be very useful tools for what is known as “water resources assessment”, a process meant to gain an integral view of the water resources status, meaning a baseline for IWRM. Moreover, they can be used to study the possible impacts and trends resulting from different kinds of scenarios, such as land use changes, population growth and climate change. However, there are plenty of hydrological models, and not everyone is suitable for any purpose or for any geographical context. Thus, with IWRM as the future application in mind, the general objective of this study was to analyze the suitability of the Soil and Water Assessment Tool (SWAT) for the specific purpose of modelling hydrological impacts of land use changes in the particular context of the Valles River Basin (VRB). This basin is located in the Huasteca Potosina, a humid/subhumid region in north- central Mexico. It constitutes the water source for the second most important city of the San Luis Potosí State and an important space for the sugarcane agribusiness. It is exposed to the impact of prolonged droughts, tropical cyclones, cold fronts and the El Niño Southern Oscillation (ENSO). The orographic barrier effect of the Sierra Madre Oriental, the shallow soils and the water extraction for irrigation and industrial purposes, among others, add to the climatic factors to make the VRB a very complex system. The frequent floodings and seasonal severe droughts are among the main issues that make it necessary to establish and consolidate a proper IWRM in this basin. The SWAT model is considered as suitable for the established modelling purpose. It was specifically developed to assess the impacts of land management practices on hydrology and water quality on a river basin scale (Neitsch, et al., 2011). After recognizing this fact, the next step was to assess its suitability for the particular (complex) context of the VRB, and the best way to do that is to evaluate its performance when calibrating and validating it. Calibration of a model is the process of ensuring that it is reproducing the real world system, in this case through the use of stream flow records, while validation is performed to evaluate model’s performance under conditions different from those used for calibration. Only when a model has been successfully calibrated and validated it is worth to be applied to simulate the desired scenarios...