Modeling the infiltration capacity of permeable stormwater channels with a check dam system

The use of permeable stormwater channels has introduced concerns over the effects of infiltration on the hydraulic behavior of their flow and the effects of flow hydraulic conditions (e.g., the water level, channel section, flow velocity, and vegetation) on the channel infiltration capacity. A check dam system provides backwater ponding, which increases the flow water depth along a channel. In this study, a channel model was used to investigate the variation in the infiltration capacity of permeable stormwater channels under different flow hydraulic conditions. Increasing the downstream check dam height and using a grass cover increased the infiltration rate and cumulative infiltration because of the decreased velocity and increased flow depth. The presence of subsurface water did not affect the hydraulic characteristics of the channel flow but decreased the cumulative infiltration because of the fast saturation of the soil. An empirical equation was developed for predicting the infiltration capacity of grassed channels in which four hydraulic parameters (i.e., the water depth, base width, side slope, and velocity) are introduced to the modified Kostiakov model. The developed model was used to calculate the runoff reduction due to infiltration along a grassed channel with and without a check dam system. The percentage of infiltrated water increased from 8 to 14% with the check dam system. The developed model can be used to predict the infiltration capacity of permeable channels for improved stormwater management and provides a valuable decision support tool for permeable channel design

EHSMu: a New Ecohydrological Streamflow Model to Estimate Runoff in Urban Areas

A conceptual lumped ecohydrological streamflow model (EHSMu) is presented as a promising tool to simulate runoff in urban catchments. The model, based on the interaction between a soil bucket and two linear reservoirs, enables also evapotranspiration and aquifer recharge to be estimated. Notwithstanding its minimalism, EHSMu describes interactions among soil moisture dynamics, hydrological fluxes and ecological processes. The model was calibrated and validated within two densely urbanized sub-basins in Charlotte (US). A Monte Carlo procedure is used to investigate the efficiency of random sets of 8 model parameters. Results show the high model performance (NSE = 0.72). The influence of land use change is evaluated, by varying the imperviousness and crop coefficients. Synthetic experiments show that increasing urbanization triggers a linear decrease in evapotranspiration and aquifer recharge, while it increases the fast runoff. An opposite response is achieved by installing vegetation with higher potential evapotranspiration, which would contribute to the actual evapotranspiration making up 50–55% of the total water balance

High accuracy capillary network representation in digital rock reveals permeability scaling functions

Permeability is the key parameter for quantifying fluid flow in porous rocks. Knowledge of the spatial distribution of the connected pore space allows, in principle, to predict the permeability of a rock sample. However, limitations in feature resolution and approximations at microscopic scales have so far precluded systematic upscaling of permeability predictions. Here, we report fluid flow simulations in capillary network representations designed to overcome such limitations. Performed with an unprecedented level of accuracy in geometric approximation at microscale, the pore scale flow simulations predict experimental permeabilities measured at lab scale in the same rock sample without the need for calibration or correction. By applying the method to a broader class of representative geological samples, with permeability values covering two orders of magnitude, we obtain scaling relationships that reveal how mesoscale permeability emerges from microscopic capillary diameter and fluid velocity distributions.Comment: Main article: 11 pages and 4 figures. Supplementary Information: 6 pages and 4 figures. Version 2 includes DOI for microCT datase

The Organization of Agricultural Production on the Southwest Periphery of the Maya Lowlands: A Settlement Patterns Study in the Upper Grijalva Basin, Chiapas, Mexico

This study investigates the issue of elite management of intensive agricultural production on terraces during the Late-Terminal Classic period (A.D. 650-950) in the Upper Grijalva Basin of Chiapas, Mexico, on the southwest periphery of the Maya lowlands. The Late-Terminal Classic represents the height of social complexity in this zone with increased population marked by construction of many residential and civic structures.A full coverage, systematic survey was conducted in two neighboring, contemporaneous polities each with differing needs for agricultural intensification due to differences in the distribution and extent of soils good for farming. In the San Lucas River Valley, characterized by the extensive distribution of relatively flat-lying soils good for agriculture, a 8.33 km2 survey recorded settlement on the margins of the Clavo Verde polity where the flat valley bottom transitions to sloping hillsides representing the likeliest location of agricultural terraces. In the Morelos Piedmont, where sloping topography and the limited distribution of soils good for farming would have presented distinct challenges to farmers, a 18.61 km2 survey recorded the extents of the core of the Morelos polity.The Late-Terminal Classic population of the Clavo Verde polity was found to be under the carrying capacity of the best agricultural lands, and the absence of agricultural terraces indicates that this intensive farming technique was not adopted. For the Morelos polity, the Late-Terminal Classic population was found to be over the carrying capacity of the best agricultural lands, and the presence agricultural terraces indicate that this subsistence technique was adopted. The small scale and simplistic forms of the agricultural terraces indicates that top-down, elite management would not have been necessary to coordinate the labor for terrace construction, maintenance and cultivation. Locally available commoner labor would have been sufficient for these activities. Furthermore, the irregular, discontinuous patterning of terraces throughout the zone suggests that their construction was not the result of elite, top-down planning. However, the strong association between elite dwellings and agricultural terraces suggests that elites may have monitored intensive agricultural production on terraces

Chiefdom Ecodynamics and Muisca Cosmology in the Valley of Leiva, Highland Colombia

e of Colombia have been the subject of much speculation and fanciful interpretation for over four centuries Not until recently however has systematic archaeological investigation identified El Infiernito as an astronomicalmeteorological observatory of the ancient Muisca culture Modern surveys have begun to reconstruct the settlement history of the Leiva Valley but little is known about the actual chiefdom community ranked kinship society for the stone observatory or how the it related to other communities in the region Argued to have functioned as a calendar monument recording solar cycles celestial alignments and forecasting weather many alternative interpretations are often uncritically accepted and fuel speculation for a local tourist industry as well as pseudoscientific fantasy No serious study has attempted to ascertain if these monuments connect to anything tangible on the natural and cultural landscapes such as actual water features and specific celestial events In an environment where effective rainfall is often insufficient or inconveniently timed for farming and alluvial farmland subject to intense erosion caused by periodic drought and flooding the cosmological importance of fertility both agricultural and human tied to vital water sources and beneficial rainfall must have been of primary concern to Muisca leaders A tangible response by a chiefly elite to such unpredictable conditions would include engineering a hydraulic landscape linked to intangible religious cosmology embodied in central stone monuments such as the monolithic observatory temple structures and artistic depictions of fertility This report discusses the subsistence and ritual roles of water at El Infiernito based on recent climate change and human ecodynamic socio-ecological dynamics of coupled human and natural systems research Recently an engineered hydraulic landscape consisting of irrigation canals check dams and drainage conduits as well as potential raise

Geomorphology, sediment analysis and restoration plan for an incised urban creek : Don Dahvee Creek, Monterey, California

The progression of urbanization throughout the state of California has had overwhelming and long-term effects on the state\u27s waterways. Don Dahvee Creek appears to be physically declining because of active channel erosion due to urbanization. This erosion has affected the amount of sediment being conveyed into Lake El Estero and the Monterey Bay. For this assessment the geometry of Don Dahvee Creek, adjacent to Whole Foods Market in Monterey, CA, was examined to determine rates of erosion. Suspended sediment concentration samples (SSC) were taken in an attempt to determine if the creek is a source of water pollution due to bank erosion, creating excess sediment downstream. Using a regression model of SSC it was found that there is no significant difference between the amount of sediment in the water entering and leaving the stream reach, during low-flow conditions. The P-values from the regression of SSC against distance downstream are much greater than .01; therefore, we fail to reject the null hypothesis at 99% confidence, leading to our conclusion that the stream banks are not generating sediment during low-flow conditions. A budget analysis used for discharge determined that there is a loss of 1/3 the water between the upper and lower culvert during low-flow conditions, possibly due to infiltration. Using cross sectional data it has been determined that the best restoration plan for Don Dahvee Creek involves dressing back and stabilizing both the bed and banks with a combination of vegetation and rock, increasing the width/depth and entrenchment ratio

A Comparative Study of Earthen Surface Finishes of the Eastern Façade of Open Area J and the Northern Façade of Open Area 26 at Cliff Palace, Mesa Verde National Park, Colorado

This thesis examines the exterior architectural surface finishes of the eastern façade of Open Area J, located in the southern end of Cliff Palace and the northern façade of Open Area 26, located in the northern end of Cliff Palace in the Speaker Chief Complex at Mesa Verde National Park. The selection of each site was based on their common incorporation of exterior façades defining an open area and the hypothesis that although Open Area J and Open Area 26 are believed to have been constructed during the same time period, dating to the 1260\u27s CE., they may be associated with different social groups or may reflect a difference between public (Speaker Chief Complex) and private architectural space. A comparative study of these two open areas considered the similarities and differences between the compositional constituents, formulation and application of the earthen surface finishes found at each site over time

Towards an antifragility framework in past human–environment dynamics

Scholarship on human–environment interactions tends to fall under two headings: collapse or resilience. While both offer valid explanatory frameworks for human–environment dynamics, both view stress as a net negative that, if unchecked, disrupts systems in equilibrium. Societies either succumb to stress (and collapse) or overcome stress and persist (demonstrate resilience). We re-evaluate the role of stress and advocate for a non-equilibrium approach to the study of past human–environment interactions. We draw inspiration from Nasim Taleb’s concept of ‘antifragility’, which posits a positive role of stress for increasingly complex systems. We apply antifragility as an explanatory framework to pre-Hispanic coastal Peru, where indigenous farmers adapted to the stresses of highly variable El Niño events through a variety of water management systems. Finally, we note that an antifragility approach highlights the beneficial role of stressors, and that avoiding stress altogether makes a system more fragile