Global terrestrial water storage capacity and flood potential using GRACE

J T Reager,J S Famiglietti

doi:10.1029/2009gl040826

Abstract

Terrestrial water storage anomaly from the Gravity Recovery and Climate Experiment (GRACE) and precipitation observations from the Global Precipitation Climatology Project (GPCP) are applied at the regional scale to show the usefulness of a remotely sensed, storage‐based flood potential method. Over the GRACE record length, instances of repeated maxima in water storage anomaly that fall short of variable maxima in cumulative precipitation suggest an effective storage capacity for a given region, beyond which additional precipitation must be met by marked increases in runoff or evaporation. These saturation periods indicate the possible transition to a flood‐prone situation. To investigate spatially and temporally variable storage overflow, a monthly storage deficit variable is created and a global map of effective storage capacity is presented for possible use in land surface models. To highlight a flood‐potential application, we design a monthly global flood index and compare with Dartmouth Flood Observatory flood maps.

Highlights

[2] Over the course of a year, many land ecosystems transition from a dry limit to a wet limit due to an annual cycle of precipitation
[4] The Gravity Recovery And Climate Experiment (GRACE) satellite mission is currently helping to close the large gaps in in-situ global hydrological data sets and providing the opportunity to investigate the nature of the Earth’s water cycle from a true global perspective [Ramillien et al, 2004; Lettenmaier and Famiglietti, 2006; Syed et al, 2008; Ramillien et al, 2008; J
[5] In this study, we introduce a quantitative, effective terrestrial storage capacity and define a flood potential index to highlight the information contained within the GRACE data that is relevant for regional flooding

Summary

Introduction

[2] Over the course of a year, many land ecosystems transition from a dry limit to a wet limit due to an annual cycle of precipitation. The benefits of the future hydrology-specific altimetry mission, SWOT [Alsdorf et al, 2007; National Research Council, 2007], and the Global Precipitation Measurement satellite [Hossain and Lettenmaier, 2006] are clear, and pre-launch studies discuss the importance of precise precipitation data and soil moisture [Entekhabi et al, 2008; Kerr et al, 2001] and surface discharge data as necessary components in an effective flood-forecasting algorithm As these studies indicate, even the best precipitation monitoring will provide only short-term flood prediction. In an ideal situation with short data latency, GRACE observations could give a one-month window of maximum flood likelihood due to regional saturation that depends on both precipitation and storage

Objectives

Methods

Results