This study examines the response of a complex lake‐wetland system to variations in climate. The focus is on the lakes and wetlands of the Prairie Coteau, which is part of the larger Prairie Pothole Region of the Central Plains of North America. Information on lake size was enumerated from satellite images and aerial photos and yielded power law relationships for different hydrological conditions. Of particular interest is a recent drought and deluge sequence, 1988–1992 and 1993–1998. Results showed that lake sizes followed well‐defined power laws that changed intra‐annually and interannually as a function of climate. The power laws for spring seasons in 1987, 1990, 1992, 1997, and 2002 have a relatively constant slope. However, slopes changed with time within each year. These lines produced from Landsat images and aerial photos describe a systematic variation in sizes for lakes ranging in area from 100 m2 to more than 30,000 m2. This tendency for lake size to follow a power law coupled with area measurement from aerial photos taken on 29 July 1939 provides a basis for reconstructing the distribution of pothole lakes in summer 1939, near the end of the Dust Bowl drought. The study shows that the areas of smaller lakes are profoundly affected seasonally by the spring snowmelt and evaporation. The areas of larger lakes are influenced more slowly by longer‐ term periods of drought and deluge.

Anticipating future global freshwater scarcity and providing mitigation require timely knowledge of spatiotemporal dynamics of discharge for gauged and, more challengingly, ungauged rivers. This study describes a coupled hydrologic (SWAT) and hydraulic (XSECT) modeling approach set in a genetic algorithm framework for estimating discharge and water depth for ungauged rivers from space. The method was tested in the Red River of the North basin by comparing simulated discharges and depths from 2006 to 2010 to in situ observations from across the basin. Results showed that calibration using only remotely sensed data (i.e., water levels from ENVISAT altimetry and water extents from LANDSAT) along the main stem of the Red River yielded daily and monthly estimates of river discharge, which correlated to measured discharges at three gaging stations on the main stem with R 2 values averaging 0.822 and 0.924, respectively. The comparisons of modeled and measured discharges were also extended to smaller tributaries, yielding a mean R 2 of 0.809 over seven gaging stations. The modeling approach also provided estimates of water depth that correlated to observations at four stations with an average R 2 of 0.831. We conclude that the integrated modeling approach is able to estimate discharge and water depth from space for larger ungauged rivers. This study also implies that in situ discharge data may not be necessary for successful hydrologic model calibration.

[1] We developed a hydrologic model capable of simulating pothole complexes composed of tens of thousands or more individual closed-basin water bodies. It was applied to simulate the hydrologic response of a prairie pothole complex to climatic variability over a 105 year period (1901 -2005) in an area of the Prairie Pothole Region in North Dakota. The model was calibrated and validated with a genetic algorithm by comparing the simulated results with observed power law relationships on water area -frequency derived from Landsat images and a 27 year record of water depths from six wetlands in the Cottonwood Lake area. The simulated behavior in water area and water body frequency showed good agreement with the observations under average, dry, and wet conditions. Analysis of simulation results over the last century showed that the power laws changed intra-annually and interannually as a function of climate. Major droughts and deluges can produce marked variability in the power law function (e.g., up to 1.5 orders of magnitude variability in intercept from the extreme Dust Bowl drought to the extreme 1993 -2001 deluge). Analyses also revealed the frequency of occurrence of small potholes and puddles did not follow pure power law behavior and that details of the departure from linear behavior were closely related to the climatic conditions. A general equation, which encompasses both the linear power law segment for large potholes and nonlinear unimodal body for small potholes and puddles, was used to build conceptual models to describe how the numbers of water bodies as a function of water area respond to fluctuations in climate.

Habitat connectivity is a landscape attribute critical to the long‐term viability of many wildlife species, including migratory birds. Climate change has the potential to affect habitat connectivity within and across the three main wetland complexes in the Great Plains of North America: the prairie potholes of the northern plains, the Rainwater Basin of Nebraska, and the playas of the southern plains. Here, we use these wetlands as model systems in a graph‐theory‐based approach to establish links between climatic drivers and habitat connectivity for wildlife in current and projected wetland landscapes and to discern how that capacity can vary as a function of climatic forcing. We also provide a case study of macrosystems ecology to examine how the patterns and processes that determine habitat connectivity fluctuate across landscapes, regions, and continents.

1] This study was designed (1) to explore the links between climate variability and the population dynamics of closed-basin surface water bodies of the Prairie Pothole Region (PPR) in North America, and (2) to test the validity of space-for-time (SFT) substitution approach for the analysis of hydrologic systems. Observational results from 1981 to 2000 show that the climate with respect to annual residual moisture (ɛ, i.e., precipitation minus potential evaporation or evapotranspiration) of the PPR changed across space (over 0.6 m) and time (over 0.3 m in central North Dakota), causing spatiotemporal variability in water areas and water body numbers. Spatial analysis of a suite of surface water complexes along a spatial ɛ gradient in the Missouri Coteau shows that a four parameter Boltzmann function quantitatively describes how the number of water bodies (N) varied as a function of 5-year average annual ɛ (R 2 = 0.76). Temporal analysis of monthly N data reconstructed by a hydrologic model also demonstrates that values of temporally varying N were highly correlated with ɛ and yielded a nearly identical Boltzmann function. This result confirms the validity of SFT substitution and suggests that detailed modern spatial data can be used to interpret hydrologic system behaviors under past or future climate conditions. This study also has important regional-scale implications for water resources management by providing a complete picture of the spatiotemporal water body distribution across the entire PPR and the potential for rapidly converting climate predictions into surface water assessments.Citation: Liu, G., and F. W. Schwartz (2012), Climate-driven variability in lake and wetland distribution across the Prairie Pothole Region: From modern observations to long-term reconstructions with space-for-time substitution, Water Resour. Res., 48, W08526,