Simulating a Watershed-Scale Strategy to Mitigate Drought, Flooding, and Sediment Transport in Drylands

Connie M. Maxwell,Alexander G. Fernald,Saeed P. Langarudi

doi:10.3390/systems7040053

Abstract

Drylands today are facing a landscape-scale water storage problem. Throughout the increasingly arid Southwest of the United States, vegetation loss in upland watersheds is leading to floods that scour soils and transport sediment that clogs downstream riparian areas and agricultural infrastructure. The resulting higher flow energies and diminished capacity to infiltrate flood flows are depleting soil water storage across the landscape, negatively impacting agriculture and ecosystems. Land and water managers face challenges to reverse the trends due to the complex interacting social and biogeophysical root causes. Presented here is an integrative system dynamics model that simulates innovative and transformative management scenarios. These scenarios include the natural and hydro-social processes and feedback dynamics critical for achieving long-term mitigation of droughts, flooding, and sediment transport. This model is a component of the Flood Flow Connectivity to the Landscape framework, which integrates spatial and hydrologic process models. Scenarios of support and collaboration for land management innovations are simulated to connect flood flow to the floodplains throughout the watershed to replenish soil storage and shallow groundwater aquifers across regional scales. The results reveal the management policy levers and trade-off balances critical for restoring management and water storage capacity to the system for long-term resilience.

Highlights

Throughout the American Southwest and many global dryland regions, drought, increased flooding, and sediment transport are exacerbating landscape-scale water challenges [1]
Note that stormwater is usually with urbanthus, areas, here the strategy is to strategy to spread and slow flood flows associated across the landscape; in but upper watershed areas, spread and slow flood flows across the landscape; in upper watershed areas, we use the term flood we use the term flood flow, and, in the valley areas with more developed infrastructure, we use the flow, and, in the valley areas with more developed infrastructure, we use the term stormwater
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Summary

Introduction

Throughout the American Southwest and many global dryland regions, drought, increased flooding, and sediment transport are exacerbating landscape-scale water challenges [1]. Less winter precipitation and higher temperatures are diminishing snowpack storage [2,3], which results in less spring runoff quantities and flow durations for downstream water users [4]. Landscape losses of deep soils and vegetative cover in this region stem from historic overgrazing and fire suppression corresponding with climate effects that began in the late nineteenth century [5,6,7]. Floods along the many river networks were more connected to more richly vegetated floodplains [7]

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Conclusion