Introduction

• Identifying drought triggers, drought prone areas and investigating the impact of potential climate changes on water resources at watershed scale.

• Developing guidelines for drought preparedness and mitigation planning.

Objectives

Materials and Methods

Conclusions/Outcomes

Acknowledgements • This study was part of a project supported by the

United States Department of Agriculture-NIFA (Award Number 2014-51130-22593) and the project entitled ‘‘Integrated plan for drought preparedness and mitigation, and water conservation at the watershed scale.’’

• Study Area: The Skunk Creek Watershed (SCW) is a tributary to Big Sioux River with a confluence within aerial extent of Sioux Falls; located in eastern part of South Dakota (SD); has an areal extent of 160,579 ha (Fig. 2).

• The land use of the SCW is dominated by cropland (63%) and grass (32%) (Fig. 3), and soil texture is dominated by silty clay loam with a few gravelly loams.

• Approach: Development of SWAT model and identification of agricultural drought triggers by monitoring the water budget for the SCW.

• The moisture sensors, temperature probes and tensiometers are installed at 6 farmers’ sites within SCW under corn-soybean rotation systems.

• Severe drought of 2012 affected 1400 counties in 33 states of the US (Fig. 1). A substantial reduction in agricultural yields was noticed.

• Due to climate change and prevailing drought conditions in on/off mode for last 15 years, ground became dry despite of intermittent/irregular rains.

• The major goal of this study is to develop a watershed-based plan for drought preparedness and water resources conservation.

Integrated plan for drought preparedness and mitigation, and water conservation at the watershed scale

Sandeep Kumara, Sushant Mehana, Ram P. Neupanea, Eric Mbonimpab, Jeppe Kjaersgaardc, Jeffrey Jacquetd, Anthony Blya, Mike Millere, and Scott Smalleyf

aDepartment of Plant Science, South Dakota State University (SDSU); bDepartment of Systems Engineering and Management, Air Force Institute of Technology, Ohio, cDepartment of Agriculture, St. Paul, MN; dDepartment of Sociology and Rural Studies, SDSU; eDepartment of Economics, SDSU; f Department of Teaching Learning and Leadership, SDSU.

• The mean annual precipitation of the study watershed was 22 mm (Fig. 4).

• SWAT model was used to delineate the SCW, and 364 HRU’s (Hydrologic Response Unit) were developed.

• SWAT model was calibrated for 1987-1994 and validated for 1995-2000 periods.

• Sensitivity analysis was carried out using SWAT-CUP (Calibration Uncertainty Program).

• The SWAT calibration for stream discharge was reasonably well with NSE and R2 values of 0.84 and 0.85, respectively for monthly simulations (Table 1).

• The simulated stream discharge resembled with the observed discharge reasonably well for both the calibration and validation periods (Fig. 5).

• SWAT outputs revealed that some years have more number of water deficit days in comparison to other years studied. This could be possible reason for decline in crop yields observed during the study period from 1987-2000.

• Soil moisture, temperature and tension are being monitored daily starting from summer 2015 for the corn-soybean rotation under conservation tillage system.

• Data gathered from soil moisture sensors, soil tensiometers, and soil temperature probes installed at different depths indicated that the soil requires more water to meet the minimum consumptive use, which is not met by rainfall alone. If not taken care of, it may adversely affect the crop yield.

Preliminary Results

• The SWAT model simulated the stream discharge reasonably well.

• The model will be used for estimating the climate change impacts on crop water use.

• Regression model will help to identify drought prone areas in the Skunk Creek Watershed.

• The project will provide a relevant way to make decision on drought preparedness and mitigation, and conserving water resources to meet crop water demand during dry periods without compromising the agricultural output.

• Awareness will be imparted to different age group students, policy and decision makers on drought preparedness and mitigation.

Project Deliverables • Mehan, S. Neupane, R., and S. Kumar. 2015.

Climate change impacts on stream discharge at Skunk Creek Watershed. Abstract submitted to International SWAT Conference and Workshops, Purdue University. October 12-16, 2015.

• Mehan, S. R. Neupane, and S. Kumar. 2015. SWAT Model Calibration, Validation and Parameter Sensitivity Analysis using SWAT-CUP. Abstract submitted for oral presentation at the International Annual Meeting at Minneapolis, MN. November 15-18, 2015.

• We will estimate the effects of potential climate change on water balance components of the agriculture dominated SCW basin using the process-based SWAT model.

• Soils and environmental parameters collected from farm sites will help to develop a regression model between the measured parameters and the soil moisture.

• Identifying the range of water conservation and management practices to ameliorate the impacts of agricultural drought that may help for sustainable agricultural production in the basin.

• Exploration for sub-surface water sources that can meet the water demands during dry periods.

• Provided additional funds are identified for the project, socio-economic aspects for adopting new technologies among the producers and other stakeholders in the watershed will be analyzed through surveys and interviews.

Fig. 2. Skunk Creek Watershed: Delineated subwatersheds (based on DEM), land use/cover (LULC), and soil texture.

Fig 1: Maps showing the occurrence of severe droughts in the United States for 2002 (left), 2012 (middle), and 2014 (right). Dark red color shows the area with exceptionally dry conditions. (Source: National Oceanic and Atmospheric Administration, NOAA, 2014).

Future Work

Table 1. The calibration and validation results of SWAT model used for simulating stream discharge for Skunk Creek Watershed.

S. No. Parameter Calibration Period Validation Period Daily Monthly Daily Monthly

1 R2 0.71 0.85 0.55 0.77 2 NS 0.56 0.84 0.42 0.77

0

50

100

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200

250

Stre

am D

isch

arge

(m

3s-1

)

Time period ( Daily time step )

Simulated Observed

Calibration Period ( 1987-1994 ) Validation Period ( 1995-2000)

Fig. 3. Locations of field sites in Skunk Creek Watershed (SCW; left), and pictures (right) taken during the field sampling, and installation of field equipments in the watershed.

Fig. 5. Model calibration and validation of stream discharge using SWAT model for the Skunk Creek Watershed.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

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4.0

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Jan Feb March April May June July August Sept Oct Nov Dec

Prec

ipita

tion

(mm

)

Stre

am D

isch

arge

(m3 s

-1)

Months

Precipitation Stream Discharge

Fig. 4. Stream discharge and monthly precipitation received at the Skunk Creek Watershed of South Dakota, USA.