Developing A Hydrologic Information System: Towards Promoting Sustainable Standardization

Water quantity and quality monitoring plays a key role towards the development of a sustainable water sector. The required infrastructure needed to monitor and manage surface and groundwater systems are often lacking particularly in developing countries. When available, water quantity and quality data are invariably fragmented, intermittent, not shared, with deficient metadata, and stored in formats that hinder establishing seamless coupling with hydrological models. Most data are saved locally with little attention placed on defining and maintaining metadata on the collection protocols, geographic referencing, measurement accuracy, resolution, detection limits, and data censorship. These limitations present serious challenges in reaching sound water management strategies. To alleviate these shortcomings, a Hydrologic Information System (HIS) based on the ArcHydro data model was developed using the country of Lebanon as a prototype. The HIS centralized available hydrological and water resources information; coupled spatial coverage with respective time series data on flow, water demand, meteorology, and water quality; and standardized metadata. Additionally, the system was structured to support hydrologic modeling and water resources analysis. A loose coupling was also integrated between the system and the Water Evaluation And Planning (WEAP) hydrological model and tested on the Upper Litani River Basin. The framework encompassed the ability to export back model simulation results and incorporate them within the HIS as time series records. The developed HIS system has since been adopted as a data repository for other water related projects in Lebanon and has helped identify key gaps in existing data and set monitoring priorities

Measurement Tool for Dynamics of Soil Cracks

Shrinkage cracks in soil function as a dominant control on the partitioning and distribution of moisture fluxes in the vadose zone. Their dynamics influence moisture balance and control water availability for runoff, deep infiltration, and near-surface storage. We present a new low-cost field instrument to monitor the temporal change in crack volume as affected by shrinkage and swelling cycles. The proposed crack-o-meter is composed of a sealed impermeable bag connected by a hose to a standpipe. An automated level logger records changes in water level in the standpipe, which correspond to volumetric changes of the crack. Results from two laboratory experiments show that the volume change observed by the crack-o-meter instruments scales linearly with the actual volume change, with an average error of 3%. The instrument was then used in a field experiment in Chile, where it measured the closing of cracks due to soil swelling

An Image-Based Method for Determining Bulk Density and the Soil Shrinkage Curve

Current laboratory methods for determining volume and bulk density of soil clods include dipping saran-coated clods in water (a destructive process due to the permanent coating), performing physical measurements on samples with well-defined geometries, or using expensive equipment and proprietary software (such as laser scanners). We propose an alternative method for determining the volume and bulk density of a soil clod, which is non-destructive, low-cost and utilizes free and open-source software. This method (the clodometer method) uses a standard digital camera to image a rotating clod, which allows for reconstruction of its three-dimensional surface and subsequent calculation of its volume. We validated the method through comparison to the standard displacement method, and then used the method to create a soil shrinkage curve for the Waldo silty clay loam soil. The method had acceptable precision (relative standard errors of the mean between 0.4 – 1.6%), which may be further improved through future software development.This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the Soil Science Society of America and can be found at: https://www.soils.org/publications/sssaj

Modeling effect of initial soil moisture on sorptivity and infiltration

A soil’s capillarity, associated with the parameter sorptivity, is a dominant control on infiltration, particularly at the onset of rainfall or irrigation. Many mathematical models used to estimate sorptivity are only valid for dry soils. This paper examines how sorptivity and its capillary component (as wetting front potential) change with initial degree of saturation. We capture these effects with a simple modification to the classic Green-Ampt model of sorptivity. The modified model has practical applications, including (1) accurately describing the relative sorptivity of a soil at various water contents and (2) allowing for quantification of a soil’s saturated hydraulic conductivity from sorptivity measurements, given estimates of the soil’s characteristic curve and initial water content. The latter application is particularly useful in soils of low permeability, where the time required to estimate hydraulic conductivity through steady-state methods can be impractical.Keywords: wetting front potential, sorptivity, capillarity, infiltration, hydraulic conductivityKeywords: wetting front potential, sorptivity, capillarity, infiltration, hydraulic conductivit

Field method for separating the contribution of surface-connected preferential flow pathways from flow through the soil matrix

Liquid latex was used as a method to seal visible surface-connected preferential flow pathways (PFPs) in the field in an effort to block large surface-connected preferential flow and force water to move through the soil matrix. The proposed approach allows for the quantification of the contribution of large surface-connected cracks and biological pores to infiltration at various soil moisture states. Experiments were conducted in a silty clay loam soil in a field under a no-till corn-soybean rotation planted to corn. Surface intake rates under ponding were measured using a simplified falling head technique under two scenarios: (1) natural soil conditions with unaltered PFPs and (2) similar soil conditions with latex-sealed large macropores at the surface. Results indicated that the contribution of flow from large surface-connected macropores to overall surface intake rates varied from approximately 34% to 99% depending on the initial moisture content and macroporosity present. However, evidence of preferential flow continued to appear in latex-sealed plots, suggesting significant contributions to preferential flow from smaller structural macropores, particularly in two out of four tests where no significant differences were observed between control and latex-sealed plots.Keywords: Tillage, Time domain reflectometry, Movement, Water content, Macropores, Solute transport, Drains, TracersKeywords: Tillage, Time domain reflectometry, Movement, Water content, Macropores, Solute transport, Drains, Tracer

Soil -water interaction: Lessons across scales

Understanding and modeling water flow behavior at the field scale is integral to various environmental and agricultural applications. Unfortunately, this understanding is challenged with preferential flows rendering the use of Darcian fluxes, developed at the laboratory scale, unable to describe the flow at the field. Preferential paths development in the field is the result of the complex interaction of multiple processes relating to the soil\u27s structure, moisture level, shrinkage induces stresses, and biological activities. Visualizing and characterizing the cracking behavior and preferential paths evolution of soils across the soil depth has always been one of the key challenges and a major barrier against scaling up existing hydrologic concepts and models to account for preferential flows. In this study, the evolution of soil\u27s internal stress due to shrinkage as well as the effect of shrinkage on TDR estimates of water contents are explored at the laboratory scale. Then, the evolution of the preferential paths volume at different soil depths and moisture conditions is assessed by a new methodology to visualize preferential paths at the field scale. Results from different soil types (the savage soil vs. the Chalmers soil) and different landuses (corn/tilled field vs. soy bean no-till fields in the Chalmers soil) are presented. Finally, the effect of introducing scaling concepts to the hydrology curriculum is explored by quantifying its effect on students\u27 enhanced knowledge and decision making skills

Not All Light Spectra Were Created Equal: Can We Harvest Light for Optimum Food‐Energy Co‐Generation?

Abstract Humanity's growing appetites for food and energy are placing unprecedented yield targets on our lands. Chasing those ever‐expanding land intensification targets gave rise to monocultures and sharpened the divide between food and energy production groups. Here, we argue that this does not have to be a zero‐sum game if food and energy can be co‐generated in the same land. Co‐generation can lead to sustainable intensification but requires a paradigm shift in the way we manage our resources, particularly light. Using an extended model of plant photosynthesis and transpiration, we demonstrate how plants react to different incident light spectra and show that manipulating light could be effective for boosting land and water efficiencies, thus potentially improving soil health. This knowledge can possibly unlock the real potential of promising modern agricultural technologies that target optimization of light allocations such as agrivoltaics. This study suggests that the blue part of the light spectrum is less efficient in terms of carbon assimilation and water use and could be more effectively used to produce solar energy, while the red part could efficiently produce biomass. A sensitivity analysis to the most important crop and environmental variables (irradiance, air temperature, humidity, and CO2 concentration) shows that plant response to different light treatments is sensitive to environmental boundary conditions and is species‐specific. Therefore, further research is necessary to assess which crops and climates are more suitable to optimize the proposed food‐water‐energy nexus