Impact of extreme drought and incentive programs on flooded agriculture and wetlands in California’s Central Valley

Point Blue Conservation Science, Petaluma, California, United States
The Nature Conservancy, Chico, California, United States
The Nature Conservancy, San Francisco, California, United States
DOI
10.7287/peerj.preprints.26483v1
Subject Areas
Conservation Biology, Ecology, Freshwater Biology
Keywords
agriculture, California, drought, water, wetlands, waterbirds, habitat incentive program
Copyright
© 2018 Reiter et al.
Licence
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
Cite this article
Reiter ME, Elliott N, Jongsomjit D, Golet GH, Reynolds MD. 2018. Impact of extreme drought and incentive programs on flooded agriculture and wetlands in California’s Central Valley. PeerJ Preprints 6:e26483v1

Abstract

Between 2013 and 2015 a large part of the western United States, including the Central Valley of California, sustained an extreme drought. The Central Valley is recognized as a region of hemispheric importance for waterbirds which use flooded agriculture and wetlands as habitat. Thus, the impact of drought on the distribution of surface water needed to be assessed to understand the effects on waterbird habitat availability. We used satellites to quantify the impact the recent extreme drought on the timing and extent of available waterbird habitat during the non-breeding season (July – May) by examining flooding in agriculture (rice, corn, and other crops) and managed wetlands across the Central Valley. We assessed the influence of habitat incentive programs, particularly The Nature Conservancy’s BirdReturns and the Natural Resources Conservation Service’s Waterbird Habitat Enhancement Program (WHEP), at offsetting waterbird habitat loss related to drought. Overall, we found significant declines in open water in post-harvest agriculture (20 – 80% declines) and in managed wetlands (47 – 59% declines) during the 2013 – 2015 drought compared to non-drought years 2000 – 2011. Crops associated with the San Joaquin Valley, specifically corn, as well as wetlands in that part of the Central Valley exhibited larger reductions in open water than rice and wetlands in the Sacramento Valley. However, seasonal wetlands on protected lands had a marginally significant (P<0.10) higher amount of open water in the drought years than those on non-protected lands. A large fraction of the daily open water in rice during certain times of the year, particularly in the fall for BirdReturns (64%) and the winter for WHEP (100%), may have been provided through incentive programs underscoring the contribution of these programs. However, further assessment is needed to know how much the incentive programs directly offset the impact of drought in post-harvest rice or simply supplemented funding for activities that might have been done regardless. Our, first of its kind, landscape analysis documents the significant impacts of the drought on freshwater wetland habitats in the Central Valley and highlights the value of using satellite data to track surface water and waterbird habitats. More research is needed to understand subsequent impacts on the freshwater dependent species that rely on these systems and how incentive programs can most strategically support vulnerable species during future drought.

Author Comment

This is a submission to PeerJ for review.

Supplemental Information

Look-up table for CVJV basins

DOI: 10.7287/peerj.preprints.26483v1/supp-1

Data for analysis of open water in agriculture fields in the Central Valley

DOI: 10.7287/peerj.preprints.26483v1/supp-2

Data used for bias correction of estimates of water from Landsat 5 and Landsat 8

DOI: 10.7287/peerj.preprints.26483v1/supp-3

Data used for Sacramento Valley level assessment of flooding in rice as part of analysis of impact of incentive programs

DOI: 10.7287/peerj.preprints.26483v1/supp-4

Data used to calculate the amount of habitat generated by incentive programs in the Central Valley

DOI: 10.7287/peerj.preprints.26483v1/supp-5

Data used to assess open water in managed wetlands in the Central Valley

DOI: 10.7287/peerj.preprints.26483v1/supp-6

R code for evaluating impact of incentive programs in the Central Valley

DOI: 10.7287/peerj.preprints.26483v1/supp-7

R-code for analyzing impacts of drought on open water in managed wetlands and agriculture using single model for all year types

DOI: 10.7287/peerj.preprints.26483v1/supp-8

R-code for analyzing wetland flooding in the Sacramento Valley and San Joaquin Valley's individually

DOI: 10.7287/peerj.preprints.26483v1/supp-9

R-code for analyzing impacts of drought on open water in managed wetlands and agriculture using separate models for each year type

DOI: 10.7287/peerj.preprints.26483v1/supp-10