Evaluation of Remote Sensing-Based Irrigation Water Accounting at River Basin District Management Scale

Jesús Garrido-Rubio,Tatiana Ortega,Alfonso Calera,Mario Belmonte,Lorena Fraile,Raquel Bravo,Irene Arellano,José González-Piqueras

doi:10.3390/rs12193187

Abstract

The Water Framework Directive in Europe requires extending metering and water abstraction controls to accurately satisfy the necessary water resource requirements. However, in situ measurement instruments are inappropriate for large irrigation surface areas, considering the high investment and maintenance service costs. In this study, Remote Sensing-based Irrigation Water Accounting (RS-IWA) (previously evaluated for commercial plots, water user associations, and groundwater water management scales) was applied to over 11 Spanish river basin districts during the period of 2014–2018. Using the FAO56 methodology and incorporating remote sensing basal crop coefficient time series to simulate the Remote Sensing-based Soil Water Balance (RS-SWB), we were able to provide spatially and temporally distributed net irrigation requirements. The results were evaluated against the irrigation water demands estimated by the Hydrological Planning Offices and published in the River Basin Management Plans applying the same spatial (Agricultural Demand Units and Exploitation Systems) and temporal (annual and monthly) water management scales used by these public water managers, ultimately returning ranges of agreement (r2 and dr) (Willmott refined index) of 0.79 and 0.99, respectively. Thus, this paper presents an operational tool for providing updated spatio-temporal maps of RS-IWA over large and diverse irrigation surface areas, which is ready to serve as a complementary irrigation water monitoring and management tool.

Highlights

AQUASTAT, the global information system on water resources, quantifies and differentiates human water abstractions based on three use categories: municipal (11%), industrial (19%), and agricultural (70%) [1]
The daily net irrigation requirements (NIR) values obtained by the Remote Sensing-based Soil Water Balance (RS-SWB) at a pixel-based spatial scale were annually aggregated by their summation to compute the spatial statistics against the different Exploitation System (ES) irrigation water management spatial scales for the whole River Basin District (RBD) in Júcar (9) and Duero (13) (Figure 1)
While the Júcar RBD provides the net annual irrigation water demands in the River Basin Management Plan (RBMP), the Duero RBD provides the annual gross irrigation water demands; to provide a coherent comparison between the published data and the model results, the global irrigation efficiency coefficient of 0.62, published by Duero RBMP, was used to convert the gross irrigation water demands into the net irrigation water demands

Summary

Introduction

AQUASTAT, the global information system on water resources, quantifies and differentiates human water abstractions based on three use categories: municipal (11%), industrial (19%), and agricultural (70%) [1]. Framework Directive, in which a common framework for similar actions related to water is proposed. Unlike the more common use of administrative or political boundaries, the Water Framework Directive selects the River Basin District (RBD) as the common geographical and hydrological unit of interest, for which the River Basin Management Plan (RBMP) is needed to provide a detailed account of how the objectives set for the RBD will be reached within the timescale required [4]. With a lifecycle of six years, the RBMPs are presently in their second cycle (the period of 2015–2021)

Methods

Results

Discussion

Conclusion