scholarly journals Climate regime and soil storage capacity interact to effect evapotranspiration in western United States mountain catchments

2014 ◽  
Vol 11 (2) ◽  
pp. 2277-2319 ◽  
Author(s):  
E. S. Garcia ◽  
C. L. Tague

Abstract. In the winter-wet, summer-dry forests of the western United States (US), total annual evapotranspiration (ET) is largely a function of three separate but interacting properties: (1) climate, especially magnitude of precipitation, its partitioning into rain or snow, and snowmelt timing; (2) soil characteristics, including soil water holding capacity and rates of drainage; and (3) the total biomass where larger, more abundant vegetation is directly proportional to greater ET. Understanding how these controls influence ET in Mediterranean mountain environments is complicated by shifts between water and energy limitations both within the year and between years. We use a physically based process model to evaluate the strength of climate controls and soil properties in predicting ET in three snow-dominated, mountainous catchments in the western US. As we expect, statistical analysis shows that annual precipitation is a primary control of annual ET across all catchments. However, secondary climate controls vary across catchments. Further, the sensitivity of annual ET to precipitation and other climatic controls varies with soil characteristics. In the drier, more snow-dominated catchments ET is also controlled by spring temperature through its influence on the timing of snowmelt and the synchronicity between seasonal water availability and demand. In wetter catchments that receive a large fraction of winter precipitation as rainfall, the sensitivity to ET is also strongly influenced by soil water holding capacity. We show that in all catchments, soil characteristics affect the sensitivity of annual ET to climatic drivers. Estimates of annual ET become more sensitive to climatic drivers at low soil water holding capacities in the catchments with the stronger decoupling between precipitation and growing season demands.

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tao Pan ◽  
Shuai Hou ◽  
Yujie Liu ◽  
Qinghua Tan

AbstractSoil water retention curve (SWRC) plays an important role in simulating soil water movement and assessing soil water holding capacity and availability. Comparison of fitness between different models to determine the best SWRC model of specific regions is required. In this study, three popular models, van Genuchten, Brooks Corey and Gardner model, were selected for comparing in a degraded alpine meadow region on the eastern Tibetan Plateau. Fitness, error distribution along with key parameters were compared. For each soil horizon, the soil moisture content at all soil water potentials decreased consistently with degradation, thereby integrally moving the SWRCs of all soil depths downward with degradation. The differences in SWRCs across various degradation degrees diminished along with soil depth and soil water potential. The Adj.r2 values of van Genuchten, Brooks Corey and Gardner models ranged in 0.971–0.995, 0.958–0.997, and 0.688–0.909, respectively. The van Genuchten and Brooks Corey models significantly (p < 0.05) outperformed the Gardner model, and have no significant differences in fitness. The fitness of all three models showed no significant changes with degradation. Regardless of degradation degree and soil depth, the fitting error of van Genuchten and Brooks Corey models was mainly distributed in the higher (from –100 hPa to –500 hPa) and lower (below –10000 hPa) potential sections. With regard to the parameters of van Genuchten and Brooks Corey models, the field capacity (θs), and permanent wilting moisture were highly coherent with Adj.r2 values of higher than 0.98, while the curve shape parameter (θr), and air entry pressure of the Brooks Corey model were much lower than those of the van Genuchten model with Adj.r2 values of lower than 0.91. The SWRCs with varying degrees of degradation are best fitted by both van Genuchten and Brooks Corey models but cannot be fitted by Gardner model. Soil water holding capacity decreased with degradation especially in the top soil (0 cm to 30 cm), but the curve shape of all SWRCs did not change significantly with degradation.


2008 ◽  
Vol 12 (3) ◽  
pp. 899-911 ◽  
Author(s):  
I. Portoghese ◽  
V. Iacobellis ◽  
M. Sivapalan

Abstract. This paper investigates the impact of various vegetation types on water balance variability in semi-arid Mediterranean landscapes, and the different strategies they may have developed to succeed in such water-limited environments. The existence of preferential associations between soil water holding capacity and vegetation species is assessed through an extensive soil geo-database focused on a study region in Southern Italy. Water balance constraints that dominate the organization of landscapes are investigated by a conceptual bucket approach. The temporal water balance dynamics are modelled, with vegetation water use efficiency being parameterized through the use of empirically obtained crop coefficients as surrogates of vegetation behavior in various developmental stages. Sensitivity analyses with respect to the root zone depth and soil water holding capacity are carried out with the aim of explaining the existence of preferential soil-vegetation associations and, hence, the spatial distribution of vegetation types within the study region. Based on these sensitivity analyses the degrees of suitability and adaptability of each vegetation type to parts of the study region are explored with respect of the soil water holding capacity, and the model results were found consistent with the observed affinity patterns.


2012 ◽  
Vol 32 (2) ◽  
pp. 538-547 ◽  
Author(s):  
潘春翔 PAN Chunxiang ◽  
李裕元 LI Yuyuan ◽  
彭亿 PENG Yi ◽  
高茹 GAO Ru ◽  
吴金水 WU Jinshui

Geoderma ◽  
2011 ◽  
Vol 160 (3-4) ◽  
pp. 355-366 ◽  
Author(s):  
Christian Piedallu ◽  
Jean-Claude Gégout ◽  
Ary Bruand ◽  
Ingrid Seynave

2017 ◽  
pp. 143-148
Author(s):  
Mahama Salifu

Maize (Zea mays L.) is the most important consuming cereal crop in the world after rice and wheat. This requires an understanding of various management practices as well as conditions that affect maize crop performance. Water deficit stress during crop production is one of the most serious threats to crop production in most parts of the world and drought stress or water deficit is an inevitable and recurring feature of global agriculture and it is against this background that field study of crops response to water deficit is very important to crop producer and researchers to maximize yield and improve crop production in this era of unpredicted climatic changes the world over.A pot experiment was carried out to determine the effects of water deficit on growth and yield formation of maize. Two maize cultivars were used Xundan20 and Zhongdan5485. Three levels of soil water content were used in two stages of water control levels at two stages of the maize plant development1. The JOINTING STAGE: A. CONTROL (CK) soil water content: from 70% to 80% of soil water holding capacity at the field, soil water content: from 55% to 65% of soil water holding capacity at the field, soil water content: from 40% to 50% of the Soil water holding capacity at the field.2. The BIG FLARE PERIOD: A. CONTROL (CK) soil water content: from 75% to 85% of soil water holding capacity at the field, soil water content: from 58% to 68% of soil water holding capacity at the field, soil water content: from 45% to 55% of the soil water holding capacity at the field.This research mainly studied the effects of water deficit on physiological, morphology and the agronomical characteristics of the maize plant at the different water stress levels.The importance of these results in this experiment will enable plant producers to focus and have a fair idea as to which stage of the maize plant’s development that much attention must be given to in terms of water supply.


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