Multifactor analysis of land use transitions in a drought-affected rice region

Context

Rapid land use change can have large impacts on water resources, local economies, supply chains, and the environment. Understanding the complexity of land use change demands analysis at multiple levels.

Objective

Our objective was to understsand the response of land use change from a 14-year drought period across the rice dominated ecosystems of California. Specifically, we quantieid when and where fields were clutviated with rice, let fallow, or converted to perennial tree crops. We studied this response in terms of crop prices, drought conditions, and soil properties.

Methods

Land use changes were analyzed from 2008 to 2021 using remotely sensed land cover data. Economic and climate data were utilized, and geospatial soil data sets were used in a machine learning framework.

Results and conclusions

While the dominant crop in the region is rice, drought led to a decrease in rice production and an increase in fallow area (up to 70,000 ha); however, during drought, walnut and almond area increased by 16,400 ha (6 % of the total rice area) due to sustained high prices for these crops. Ironically, orchard crops have greater water demand than rice, requiring a regular annual supply of water. The shift to orchard crops was limited to soils with a lower clay content (<40 % clay). The interior basins of this region have higher clay content, and it is unlikely that under current conditions these soils will shift to crops other than rice.

Significance

This study demonstrates how biophysical, environmental, and economic forces can drive and constrain land use changes in the short-term. Understanding these short-term dynamics has important implications for long term planning and policy making.