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Abstract: This paper develops a forestland management model for the three states in the South Central United States (Arkansas, Louisiana, and Mississippi). Forest type and land-use shares are estimated to be a function of economic and physical variables. The results suggest that while historically pine plantations in this region have been established largely on old agricultural land, in the future pine plantations are likely to occur on converted hardwood-forest lands. This shift in the supply of land for plantations could have large effects on above-ground carbon storage and other ecosystem services. Subsidies of approximately $12–27 per ha per year would maintain the area of hardwood forests and reduce carbon emissions from the above-ground and product pool carbon stocks over the next 30 years. Across the several scenarios considered, results suggest that maintaining hardwoods could be an efficient carbon sequestration alternative. [Copyright &y& Elsevier]

To study the potential impacts of climate change on air quality and public health over the eastern United States, a coupled global/regional-scale modeling system consisting of the NASA-Goddard Institute for Space Studies Atmosphere–Ocean model, the MM5 mesoscale meteorological model and the Community Multiscale Air Quality (CMAQ) model for air quality has been developed. Evaluation results of the modeling system used to simulate climate and ozone air quality over the eastern United States during the five summers of 1993–1997 are presented in this paper. The results indicate that MM5 and CMAQ capture interannual and synoptic-scale variability present in surface temperature and ozone observations in the current climate, while the magnitude of fluctuations on shorter time scales is underestimated. A comparison of observed and predicted spatial patterns of daily maximum ozone concentrations shows best performance in predicting patterns for average and above-average ozone concentrations. The frequency distributions of the duration of extreme heat and ozone events show similar features for both model predictions and observations. Finally, application of a synoptic map-typing procedure reveals that the MM5/CMAQ system succeeded in simulating the average ozone concentrations associated with several frequent pressure patterns, indicating that the effects of synoptic-scale meteorology on ozone concentrations are captured by the modeling system. It is concluded that the GCM/MM5/CMAQ system is a suitable tool for the simulation of summertime surface temperature and ozone air quality conditions over the eastern United States in the present climate. [Copyright &y& Elsevier]

Alluvial fans occur in all climatic and tectonic environments. However, most descriptions of fan features and sediments have focused on arid and semiarid regions. This paper describes the sediments and soil ages on 63 alluvial fans in a subhumid climate (mean annual precipitation of 45–52 cm). SSURGO soil data were merged with geologic and topographic data in the ArcMap© GIS platform to develop a series of maps showing variations across fan surfaces in sediment textures and surface stability ages. Particle size data (percent cobble and percent total gravel) from the upper 150 cm of sediments cluster into six textural groups that are aligned along a trend of decreasing gravel percentage (decreasing stream capacity) and decreasing cobble percentage (decreasing stream competency). The groups of higher cobble and gravel percentages extend from fan apex to toe in both the shallow (<50 cm depth) and deeper (>100 cm depth) layers with groups of lower cobble and gravel percentage occurring along fan margins in the shallow (<50 cm depth) layer. The thickness of B and Bt horizons from representative soil profiles were used to calculate proportional soil ages based on 10Be residence times in loessial Bt horizons and correlation of gravelly fan soils to similar gravelly soils on nearby Pinedale outwash. This approach identified six stability episodes since the end of the Bull Lake beginning at ~100 ka, ~38 ka, ~27 ka, ~16 ka, ~10 ka, and <2 ka. The proportional soil ages correlate closely with fan chronologies constrained by TL and OSL ages in nearby areas. Soil ages and sediment textural groups differed between fan populations along the mountain front with active faulting and those along the stable mountain front. Fan stability surfaces older than 16 ka are preserved only at fault termini. Holocene faulting resulted in fans with (1) coarser sediments, (2) younger sediments, (3) progressive onlap of younger sediments, (4) the absence of relic fan surfaces, landslides and colluvium at the mountain front, and (5) the onlap of alluvial fans onto the floodplain of the axial stream. Sediment pulses related to individual fault events could not be definitively identified because of concurrent climatic changes. The study demonstrates that both climatic and tectonic conditions influence sediment textures and fan surfaces ages. • Sediments cluster into six groups reflecting progressive changes in stream power • The same high capacity/high competency textural groups dominate all fan sediments • Six fan-surface stability episodes since Bull Lake (100, 38, 27, 16, 10, and < 2 ka) • Relict fans >38 ka only occur at fault termini; elsewhere fan surfaces are <16 ka • Identified fan-stability episodes are regional and correspond to climate changes [ABSTRACT FROM AUTHOR]

• A HB framework is used to consider similarity of adjacent basins to restrain time-varying parameter. • Four scenarios were developed to explore the spatial coherence between adjacent basins. • The proposed method succeeded in reducing the uncertainty of time-varying parameters. • The seasonality of the catchment storage was more coherent between adjacent basins. Hydrological processes became non-stationary under the influences of climate change and human activities. This non-stationarity highlights the need to adopt time-varying parameters in hydrological models. The majority of existing literature quantifies time-varying parameters by incorporating real observations of single basin into a hydrological model. They are limited in their information on catchment characteristics and climatic factors to constrain time-varying parameters. Thus, models are difficult to apply for hydrological predictions outside the calibration periods. This paper formulated the time-varying parameters for a lumped hydrological model as explicit functions of physically-based covariates that captured the catchment characteristics. Then, it used a hierarchical Bayesian framework to incorporate the similarity of adjacent basins to reduce the uncertainty of the assumed functions for time-varying parameters. Four modeling scenarios were developed to explore the spatial coherence between different characteristics of adjacent basins. Five criteria were adopted to evaluate the performance of assumed functional forms. Four spatially adjacent catchments in the central United States were selected as case studies to examine the validity of the proposed method. Results showed that (1) the proposed method succeeded in reducing the uncertainty of time-varying parameters, and (2) the seasonality of the catchment storage was more coherent between adjacent basins, indicated by the largest increase in model prediction performance (i.e., 9%). This study improved the understanding of the spatial coherence of time-varying parameters, which helps improve hydrological predictions in the future. [ABSTRACT FROM AUTHOR]