Modeling 25 years of spatio-temporal surface water and inundation dynamics on large river basin scale using time series of Earth observation data

Valentin Heimhuber,Mirela G Tulbure,Mark Broich

doi:10.5194/hess-20-2227-2016

Valentin Heimhuber, Mirela G Tulbure + Show 1 more

Open Access

https://doi.org/10.5194/hess-20-2227-2016

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Abstract

Abstract. The usage of time series of Earth observation (EO) data for analyzing and modeling surface water extent (SWE) dynamics across broad geographic regions provides important information for sustainable management and restoration of terrestrial surface water resources, which suffered alarming declines and deterioration globally. The main objective of this research was to model SWE dynamics from a unique, statistically validated Landsat-based time series (1986–2011) continuously through cycles of flooding and drying across a large and heterogeneous river basin, the Murray–Darling Basin (MDB) in Australia. We used dynamic linear regression to model remotely sensed SWE as a function of river flow and spatially explicit time series of soil moisture (SM), evapotranspiration (ET), and rainfall (P). To enable a consistent modeling approach across space, we modeled SWE dynamics separately for hydrologically distinct floodplain, floodplain-lake, and non-floodplain areas within eco-hydrological zones and 10km × 10km grid cells. We applied this spatial modeling framework to three sub-regions of the MDB, for which we quantified independently validated lag times between river gauges and each individual grid cell and identified the local combinations of variables that drive SWE dynamics. Based on these automatically quantified flow lag times and variable combinations, SWE dynamics on 233 (64 %) out of 363 floodplain grid cells were modeled with a coefficient of determination (r2) greater than 0.6. The contribution of P, ET, and SM to the predictive performance of models differed among the three sub-regions, with the highest contributions in the least regulated and most arid sub-region. The spatial modeling framework presented here is suitable for modeling SWE dynamics on finer spatial entities compared to most existing studies and applicable to other large and heterogeneous river basins across the world.

Highlights

Inundated areas such as floodplains play a major role in the healthy function of river systems and perform many ecosystem services of value to people such as the retention of flood water, nutrients, and sediment and the provision of food, clean water, and groundwater recharge (Hamilton, 2010; Lemly et al, 2000; Maltby and Acreman, 2011; Robertson et al, 1999; Tockner et al, 1999)
We expected Q lags to be in the same range as the Q lags of the surrounding floodplains, with potential minor differences resulting from the larger volume and slower filling behavior of these water bodies compared to shallow floodplains
We developed a spatial modeling framework that allowed us to apply a tailored modeling approach to hydrologically distinct floodplain, floodplain-lake and non-floodplain areas and to quantify local driver combinations on the level of 10 km × 10 km grid cells

Summary

Introduction

Inundated areas such as floodplains play a major role in the healthy function of river systems and perform many ecosystem services of value to people such as the retention of flood water, nutrients, and sediment and the provision of food, clean water, and groundwater recharge (Hamilton, 2010; Lemly et al, 2000; Maltby and Acreman, 2011; Robertson et al, 1999; Tockner et al, 1999). Floodplains are important within water stressed areas with high rainfall variability and semi-arid climate conditions as they help to sustain smaller discharges during the dry season, resulting in improved overall availability of water (Teferi et al, 2010). During the last century, increasing development of water resources, land use transformations, and agricultural intensification have led to an alarming disappearance and decline of terrestrial surface water resources (Finlayson and Spiers, 1999; Jones et al, 2009; Lemly et al, 2000). There is a pressing need for improved management and restoration of terrestrial surface water resources, which requires cost-effective methods for mapping and analyzing the distribution and dynamics of surface water across large spatial and temporal scales. Heimhuber et al.: Modeling 25 years of spatio-temporal surface water (Alsdorf et al, 2007; Bakker, 2012; Finlayson et al, 1999; Vörösmarty et al, 2015)

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