Assessing Streamflow Alteration from Land-Use and Land Cover Changes
using Long Short-Term Memory Neural Networks
Abstract
Changes in land-use and land cover (LULC) occur in response to economic
development and the growing demand for food. However, the impact on
water availability for downstream users is often overlooked in land
management policies, likely because of the lack of a well-established
approach for evaluating the impact of LULC changes on river flows. This
study explores the use of long short-term memory (LSTM) networks trained
on data from thousands of stream gauges across the United States (US).
Three LSTM networks were considered, each using different levels of LULC
information: none, static (constant) and dynamic (updated annually). For
this study, we created the DROMEDARY US dataset that incorporates the
Cropland Data Layer dataset from the US Department of Agriculture,
reflecting significant human-related LULC changes, and includes
significantly more basins (3,246) than existing datasets commonly used
for benchmarking hydrological models. All LSTMs demonstrated good
out-of-sample prediction skills across the US. However, the ones using
dynamic LULC information outperformed the others by a significant margin
in reproducing observed changes in flow following changes in fallowing,
an agricultural practice used to let the land rest after intense
cropping cycles, or to spare water during droughts. Interestingly, using
static LULC information performed worse than using no LULC information,
highlighting that use of inaccurate (or outdated) information can
degrade model performance at reproducing the effect of change in LULC,
while having good streamflow prediction skill. Scenarios involving
increased fallowed land highlighted further the benefits of using
dynamic, emphasizing the need for frequently updated LULC datasets.