Ajay Kalra

Improving Streamflow Reconstructions Using Oceanic-Atmospheric Climate Variability

Recurring hydrologic drought in Southwestern U.S. has raised questions about the reliability of future water supplies. Streamflow reconstruction using tree-ring chronologies (TRC) is used traditionally to expand the length of past streamflow records, which are helpful in long-term planning of water resource especially by giving information about duration and severity of past regional drought events. This study focuses on improving reconstruction methodology using TRC, by incorporating Sea Surface Temperature (SST) and climate indices of Pacific Decadal Oscillation and Southern Oscillation Index, as predictors, in a stepwise linear regression model. The approach is tested on six unimpaired streamflow gages in the Rio Grande Basin, located in the western U.S. Reconstructions are performed from 1856-2002. Results showed SST as the more influential predictor compared to using TRC only and climate indices. Future work will involve applying the modeling approach in other Western U.S. river basins. Introduction Streamflow is a vital source of water supply. Climate variability is expected to affect streamflow (Dawadi and Ahmad, 2012, Forsee and Ahmad, 2011), and thus may lead to conditions reflected in the form of droughts (Stephen et al., 2010; Puri et al., 2011a) or floods (Mosquera-Machado and Ahmad, 2007; Puri et al., 2011b; Ahmad et al., 2010; Ahmad and Simonovic, 2000; 2001). Climate variability coupled with increasing population calls for sustainable water management for municipal, agricultural, environmental, and public health needs (Wu et al., 2013; Vedwan et al., 2008; Kalra and Ahmad, 2012; Dawadi and Ahmad, 2013; Qaiser et al., 2011; Shrestha et al, 2011; Venkatesan et al., 2011a; Ghumman et al., 2013; Melesse et al., 2011; Impoinvil et al., 2007a; 2007b). Long-term streamflow records can help in understanding the range of flow variability and developing water management strategies (Foster, 2008; Mirchi et al. 2013). The available instrumental data is usually limited and thus might be insufficient to describe the long-term hydrologic variability of a region (Carrier et al., 2013). Streamflow reconstruction, by increasing the length of the data, is an important tool to understand past hydrology (Woodhouse and Lukas, 2006). 846 World Environmental and Water Resources Congress 2014: Water without Borders

Investigation of the Linkages between Oceanic Atmospheric Variability and Continental U.S. Streamflow

This study evaluated the long term changes (trend and step) and investigated the possible influences of two indicators of oceanic-atmospheric climate variability, i.e., sea surface temperatures and 500 mbar geopotential height index, on 864 unimpaired water year streamflows in the continental United States. Two nonparametric tests, i.e. Mann-Kendall and Pettitt test, were used to evaluate the changes. Singular value decomposition (SVD) was used to evaluate the association between oceanic-atmospheric indices and streamflow. The change results indicated increasing streamflow patterns in the eastern United States and dominant, decreasing streamflow trends in the Pacific Northwest and South Atlantic Gulf regions with statistically significant step changes occurring during the early 1970s and 1980s. SVD results showed the Pacific SSTs had strong correlations with the Midwest and southern South Atlantic-Gulf and Pacific Northwest regions, whereas the Atlantic SSTs showed strong correlations with New England, South Atlantic-Gulf, and Upper and Lower Colorado regions.

Using Wavelet to Analyze Periodicities in Hydrologic Variables

The trend and shift in the seasonal temperature, precipitation and streamflow time series across the Midwest have been analyzed, for the period 1960-2013, using the statistical analyses (MannKendall test with and without considering short term persistence (MK2 and MK1, respectively) and Pettitt test). The paper also utilizes a relatively new approach, wavelet analysis, for testing the existence of trend and shift in the time series. The method has the ability to decompose a time series in to lower (trend) and higher frequency components (noise). Discrete wavelet transform (DWT) has been employed in the present study with an aim to find which periodicities are mainly responsible for trend in the original data. The combination of MK1, MK2 and DWT along with Pettitt test hasn’t been extensively used up to this time, especially in detecting trend and shift in the Midwest. The analysis of climate division temperature and precipitation data and USGS naturalized streamflow data revealed the presence of periodicity in the time series data. All the incorporated time series data were seasonal to analyze the trends and shifts for four seasons-winter, spring, summer and fall independently. D3 component of DWT were observed to be influential in detecting real trend in Temperature, precipitation and streamflow data, however unlike temperature, precipitation and streamflow showed decreasing trend as well. Shift was relatively observed more than trend in the region with dominance of D3 component in the data. The result indicate the significant warming trend which agrees with the “increasing temperature” observations in the past two decades, however a clear explanation for precipitation and streamflow is not obvious.

Response of Climate Change on Urban Watersheds: A Case Study for Las Vegas, NV

The current research is a partnering effort between Southern Illinois University Carbondale and City of Las Vegas to assess the vulnerability to drought, extreme heat, and extreme precipitation. This study focuses on precipitation and uses different climate scenarios from the high-resolution North American Regional Climate Change Assessment Program (NARCCAP) climate model data to evaluate the existing stormwater infrastructure of the Gowan watershed in the Las Vegas valley. Six NARCCAP models considered in the study have shown the Gamma distribution as the best fitted from Kolmogorov Smirnov best fit test. Delta change method is adopted to quantify the effect of climate change on storm depth. U.S. Army Corps of Engineers HEC-HMS model is used to evaluate the changes in peak flow, storage, and outflow within the watershed. The findings of the analysis show that the drainage facility of the study area is vulnerable to the related climate change impacts. This study helps to quantify the effect of climate change on design storm depth of urban watershed.

Coupling HEC-RAS and HEC-HMS in Precipitation Runoff Modelling and Evaluating Flood Plain Inundation Map

The climate change and land use change have raised the challenges associated with increased runoff and flood management. The risks associated with flooding have been increasing with development in flood plain and changing climate resulting in increase in inundation of flood plain. The current study will help to evaluate the extent of flood plain in the study area – Copper Slough Watershed (CSW) in Champaign, Illinois; utilizing the known precipitation and land use. The study of CSW is taken into account, as this is the largest watershed of Champaign City and had undergone major land use change increasing the flooding issues in the region. The conducted research utilizes the Hydrologic Engineering Center Hydrologic Modelling System (HECHMS) and Hydrologic Engineering Center – River Analysis System (HEC-RAS) as the modelling tool to develop runoff and floodplain inundation evaluation model for known precipitation. The model also incorporates Aeronautical Reconnaissance Coverage Geographic Information System (ARCGIS) extensionsHEC-GeoRAS and HEC-GeoHMS for the spatial analysis of the watershed. The hydrologic analysis is performed using HEC-HMS while the hydraulic modeling is done using HEC-RAS. Forcing the model with forecasted precipitation can also help with flood warning system by generating pre-flood inundation maps.

Ice-Cover and Jamming Effects on Inline Structures and Upstream Water Levels

River ice cover is a reoccurring phenomenon in the Northern United States every year. Sheets and layers of ice result in a rise of water surface elevation and may lead to ice jams in a river. This research explains the modeling of a river reach through Northern Illinois containing a structural weir and how the water profile is effected during ice cover and ice jam events. The Hydraulic Engineering Center’s River Analysis System was used in conjunction with Esri ArcMap software to model a portion of the river for analysis. The study area of the Rock River flowing through Oregon, IL is known to freeze and ice over during the winter months in Northern Illinois. Data from the United States Geological Survey and National Oceanic and Atmospheric Administration were utilized to obtain cross-section and discharge measurements. The impacts of an ice jam occurring upstream of the weir and downstream of the weir were studied. The effects of the ice jam on the upstream water levels were also evaluated to observe if any flooding may occur inside the town or even farther upstream. Results of the ice cover and ice jam data were then compared to those of the Rock River under normal open flow conditions thus observing the change in water level, Froude number, and flow velocity. Results from this study help to point out the significance of ice jam occurrences and their effects on inline structures and future flooding concerns in the surrounding area.

Multi-Scale Correlation Analyses between California Streamflow and ENSO/PDO

El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) are two of the most important climate indices that influence the western U.S. hydrology significantly. This study evaluated how these two indices have influenced California streamflow over the years and determined their correlation at multiple time-scales. Data were obtained from 14 unimpaired streamflow stations of California for a study period of 63 years (i.e., 1951 to 2013). The concept of continuous wavelet transform was applied to observe the variance in each time-series at multiple time-scale bands over the years. The correlation was found to be higher in the latter half of the study period. ENSO showed a higher correlation with California streamflow compared to PDO across the study period. The results of this study can be of assistance in determining the relationship between Pacific SST fluctuation and California streamflow. The findings may help understand the recent California drought as well.

A Conceptualized Groundwater Flow Model Development for Integration with Surface Hydrology Model

A groundwater system model was developed and calibrated in the study area of Lehman Creek watershed, eastern Nevada. The model development aims for integrating the surface hydrologic model Precipitation Runoff Modeling System (PRMS) model with the three-dimensional (3D) finite-difference model MODFLOW. A two-layer groundwater model was developed with spatial discretization of 100 x 100 m grid. The water balance was estimated with inflows of gravity drainage and initial streamflow estimated from a calibrated PRMS model, and with outflows of spring discharges, boundary fluxes, and stream base flow. A steady-state model calibration was performed to estimate the hydraulic properties. The modeling results were able to represent the geographic relieves, simulate water balance components, and capture the hydrogeologic features. The preliminary results presented in this study provide insights into the local groundwater flow system and lay groundwork for future study of interactive influences of surface hydrologic variation.

Precipitation and Indian Ocean Climate Variability-A Case Study on Pakistan

The study evaluated the relationship between two climate variability indicators – seasurface temperature (SST) and 500-mbar geopotential height (HGT/Z500) – and the monsoonal precipitation pattern of Pakistan. Data from 30 precipitation gauges were obtained and were analyzed over a period of 35 years from 1980 to 2014. Singular-valued decomposition (SVD) technique was used to determine the association of previous year’s SST and HGT with the current year’s monsoonal precipitation. The results indicated that the association of SST and HGT with precipitation varied depending on the lead-times selected. Multiple regions of the North Indian Ocean were identified that showed significant association in affecting Pakistan’s precipitation. The long term trend and abrupt shift patterns of precipitation were also evaluated across the selected gauges to determine the generic change patterns. The findings of the study can be useful predictors of forecasting models for water management in Pakistan.

Improvements to SIU’s Engineering Campus Parking and Walkways along Campus Lake

Understanding the performance of natural and engineered infrastructure to reduce stormwater runoff is important in selection of management options. One of the many ways used to reduce or redirect storm water runoff is by introducing rain gardens/bioretention basins and/or pervious pavements. This study describes the results of a theoretical experiment conducted around Southern Illinois University—Carbondale’s (SIUC) College of Engineering parking lots. The project areas, approximately seven acres, includes parking for visitors and staff and some walking paths with green space. The location has been prone to flooding in the past. The study investigated the cost and feasibility of introducing rain gardens and pervious pavements around the lots to reduce storm water runoff and limit its impact on the surrounding area. Storm event data for the area were referenced to recreate specific design conditions, and geographic information systems (GIS) in combination with the Environmental Protection Agency’s Storm Water Management Model (EPA SWMM) were used for analysis. With the introduction of pervious pavements and retention areas, the goal of this study was reducing flooding around building access points and walkways frequented by students. Pervious pavements were introduced in the design to decrease initial runoff volumes and distribute excess runoff to retention areas. Overall, the study focused on reducing the volume of runoff, through pervious pavements and collection areas, on two sites at SIUC’s Campus.