Changes In Soil Water Storage Research Articles

Ecohydrological assessment of the water balance of the world's highest elevation tropical forest (Polylepis)

Polylepis trees grow at elevations above the continuous tree line (3000–5000 m a.s.l.) across the Andes. They tolerate extreme environmental conditions, making them sensitive bioindicators of global climate change. Therefore, investigating their ecohydrological role is key to understanding how the water cycle of Andean headwaters could be affected by predicted changes in environmental conditions, as well as ongoing Polylepis reforestation initiatives in the region. We estimate, for the first time, the annual water balance of a mature Polylepis forest (Polylepis reticulata) catchment (3780 m a.s.l.) located in the south Ecuadorian páramo using a unique set of field ecohydrological measurements including gross rainfall, throughfall, streamflow, and xylem sap flow in combination with the characterization of forest and soil features. We also compare the forest water balance with that of a tussock grass (Calamagrostis intermedia) catchment, the dominant páramo vegetation. Annual gross rainfall during the study period (April 2019–March 2020) was 1290.6 mm yr−1. Throughfall in the Polylepis forest represented 61.2 % of annual gross rainfall. Streamflow was the main component of the water balance of the forested site (59.6 %), while its change in soil water storage was negligible (<1 %). Forest evapotranspiration was 54.0 %, with evaporation from canopy interception (38.8 %) more than twice as high as transpiration (15.1 %). The error in the annual water balance of the Polylepis catchment was small (<15 %), providing confidence in the measurements and assumptions used to estimate its components. In comparison, streamflow and evapotranspiration at the grassland site accounted for 63.7 and 36.0 % of the water balance, respectively. Although evapotranspiration was larger in the forest catchment, its water yield was only marginally reduced (<4 %) in relation to the grassland catchment. The substantially higher soil organic matter content in the forest site (47.6 %) compared to the grassland site (31.8 %) suggests that even though Polylepis forests do not impair the hydrological function of high-Andean catchments, their presence contributes to carbon storage in the litter layer of the forest and the underlying soil. These findings provide key insights into the vegetation-water‑carbon nexus in high Andean ecosystems, which can serve as a basis for future ecohydrological studies and improved management of páramo natural resources considering changes in land use and global climate.

Water Balance Characteristics of the Salix Shelterbelt in the Kubuqi Desert

Water shortages are the main factor restricting the survival and construction of shelterbelts in sandy areas. Comprehensive analysis of the water balance characteristics of forest stands is crucial for scientifically understanding and regulating the water supply of shelterbelts in sandy areas and formulating appropriate vegetation cultivation and restoration strategies. We simultaneously monitored outer-forest precipitation, canopy interception, stemflow, throughfall, forest transpiration, understory evapotranspiration, and soil moisture content changes in the Salix forest in the Kubuqi Desert during the main growing season (June–October) of 2022. The results showed that the total evapotranspiration of the forest was 185.62 mm, and the components and their proportions of precipitation during the same period were as follows: forest floor evapotranspiration, 94.43 mm (35.88%); stand transpiration, 68.34 mm (25.97%); and canopy interception, 22.85 mm (8.68%). Based on the water balance of the 0–60 cm soil layer and by integrating the changes in soil water storage and the influence of external water transport, the net runoff of the forestland was calculated to be approximately 77.58 mm; that is, the water balance requirements for growth were met. In the future, appropriate irrigation and supplementation can be carried out in June and July to ensure healthier growth in the shelterbelt, and plant photosynthesis and internal physiology can be further studied for cultivation in other desert areas.

2005–2017年中国干旱半干旱区典型生态系统土壤储水量数据集

Soil water is one of the important components of the earth's water resources, and also the main source of water directly consumed by vegetation and crops. Therefore, the storage, recharge, consumption, renewal and balance of soil water are of great significance to agriculture, animal husbandry, forestry, ecological environment and water resources balance, especially for the arid and semi-arid region of China. We collect and sort out the long-term observation data of soil moisture from eight ecosystem observation and research stations of the Chinese Ecosystem Research Network (CERN) located in the arid and semi-arid region of China during 2005 - 2017, and generates the corresponding soil water storage dataset through quality control, spatial and temporal normalization, statistical calculation, in order to provide long-term data support for understanding distribution and change of soil water storage in typical ecosystems in arid and semi-arid areas of China.

Sub-Shrub Components Change the Soil Water Storage Response to Daily Precipitation and Air Temperature in the Loess Plateau

Soil water shortage has become a severe issue in ecological restoration and sustainable development in the Loess Plateau, facing the challenges of climate change and vegetation restoration. This study monitored the soil water content in surface soil (0–40 cm) with different sub-shrub component treatments, including the natural condition (NC), the canopy plus the roots (CR) and only the roots (OR), to analyze the change in soil water storage (∆W) and its response to precipitation (P) and air temperature (Ta) on a daily scale. P was the main factor controlling the daily ∆W, contributing 49–52% to the variation in the daily ∆W, and Ta only explained 6–21% of the variation. Minimum P amounts of 0.74–1.12 mm and maximum Ta of 29.09–32.00 °C were the thresholds required to increase soil water storage (W). Sub-shrub components showed significant influences on soil water conservation. We found that the ∆W hierarchy for each sub-shrub treatment was NC (1.73 mm) &gt; CR (0.71 mm) &gt; OR (0.56 mm) on rainy days and NC (−0.53 mm) &lt; CR (−0.36 mm) &lt; OR (−0.06 mm) on no-rain days. Additionally, the hierarchy of the rainwater retention rate was NC (26.43%) &gt; OR (13.71%) &gt; CR (4.58%). Thus, a canopy could increase infiltration and hugely consume soil water at the same time, while litter could weaken or offset the canopy’s effects and the roots promote infiltration with little evaporation loss.

Positive effects of mixed-species plantations on soil water storage across the Chinese Loess Plateau

Soil water storage (SWS) is a key variable influencing hydrological processes and vegetation function in arid and semiarid regions. Although convincing evidence indicated that mixed forests have higher resistance and resilience to climate change and natural disturbance than monocultures, it is unclear how mixed-species plantations affect SWS. By conducting a meta-analysis of 1071 paired observations in mixed-species plantations and monoculture plantations from 45 studies, we showed that, on average, the SWS of mixed-species plantations at 0–500 cm was 10.81% higher than that of monoculture plantations. Importantly, these positive mixture effects increased over time, with greater positive effects in mixed tree and shrub plantations. The effects of mixed-species plantations on SWS shifted from positive to negative with increasing soil depth, and these mixing effects in the topsoil layer (0–100 cm) became more pronounced with increasing stand age. However, the mixture effects on SWS did not vary with the mean annual temperature and precipitation. Moreover, mixed-species plantations were more conducive to enhancing the SWS capacity in areas with a low initial SWS. Structural equation models demonstrated that stand age was the main factor controlling the change in SWS, and soil depth also reduced the effect size of SWS by influencing the initial SWS. Our findings highlight that protecting and promoting functionally diverse forests improves SWS capacity, thereby alleviating soil moisture stress in arid and semiarid regions.

Soil‐water response in a volcanic ash hillslope affected by fissures and microtopographic changes caused by the Kumamoto earthquake, in Japan

AbstractWe examined soil‐water response in a hillslope with multi‐layered volcanic soils affected by fissures formed by intense shaking during the 2016 Kumamoto earthquake in Japan. Pressure head and volumetric water content responses in a 6 × 20 m hillslope ridgeline plot were monitored by tensiometers and capacitance‐based soil moisture sensors, respectively. The plot contained seven seismic fissures (0.3–0.8 m deep and 0.4–2.2 m wide) formed parallel to the ridgeline that exposed underlying soil layers, while areas with topsoil occurred between the fissures. Among the alternating layers, the andisol (ca. 1.0 m deep) consistently experienced high pressure heads (&gt;−150 cm H2O) and volumetric water contents (&gt;0.58 cm3 cm−3), indicating high water‐holding capacity. This andisol was a key layer for storing soil water and causing slow drainage into the deeper matrix, resulting in abrupt increases in volumetric water content during storms. Rainwater directly reaching the bottom of fissures without percolating through the topsoil caused rapid soil‐water response compared to the soil layer where water percolated via topsoil. Analysis of in‐situ soil water retention curves, recession rates and water storage changes revealed that the second andisol had unique characteristics for retaining water in the hillslope. The findings of this study show that spatial and temporal variability of soil water responses varied associated with earthquake‐induced fissure formation and soil water characteristics of multi‐layered volcanic soils.

Empirical equations for estimating field capacity in dryland cropping soils of southeastern Australia

The root zone soil water content at field capacity, θFC, is often crucial for irrigation scheduling and soil-plant-atmosphere modelling. Although θFC is traditionally determined using methodologies based on matric head or when water flux at the bottom of the root-zone equal to a prescribed negligible flux, these approaches can be problematic for some soils and applications. In this study, a novel water storage approach was used to estimate θFC for 11 soil texture classes in southeastern Australia (northwest Victoria) by employing the Soil-Water-Atmosphere-Plant (SWAP) model to simulate gravity drainage from saturation in the active root zone (top 60 cm). Field capacity was specified as the average root zone water content corresponding to a 1% relative change in daily soil water storage. We have also estimated flux-based θFC when prescribed flux at the bottom of the root-zone was 0.1 cm d-1. Three new empirical equations were developed to estimate storage-based θFC as a function of SWAP-simulated drainage flux out of the root zone, the n parameter of the van Genuchten function, and the saturated soil hydraulic conductivity, Ks, or the soil water content at − 100 cm matric head. We have evaluated these three new equations in addition to nine published equations for estimating θFC. The three new equations were found to be better predictors of θFC than most of the nine popular equations reported in the literature when compared to flux-based θFC values. Based on findings from this study the new equations are considered to be effective for irrigation scheduling and crop/climate modelling on the dryland soils of Victoria. Future studies will assess the applicability of the new equations to other parts of Australia.

Responses of soil water dynamics to precipitation events in an alpine meadow ecosystem of the Qinghai Lake Basin based on high‐precision lysimeter measurements

AbstractIn high‐altitude cold areas, how precipitation and freeze–thaw processes affect soil water dynamics is not well understood due to a lack of high real‐time resolution measurements. This study measured soil water balance components with a high‐precision lysimeter in an alpine meadow ecosystem in the Qinghai Lake watershed from June 30, 2020, to June 30, 2021. The results showed that the total precipitation (TP), evapotranspiration (ET), soil water storage change (ΔS) and the vertical water flow (WF) of this ecosystem were 705.18, 633.21, 72.58 and −0.60 mm, respectively, during the study period. Continuous wet days with precipitation events larger than 10.00 mm led to percolation, while continuous dry days with strong ET caused an upward WF. Pearson correlation analysis suggests that a larger instantaneous precipitation intensity may be more conducive to an increase in shallow soil moisture (R2 &gt; 0.72, p &lt; 0.05). Furthermore, the TP thresholds in the complete thawing period inducing the soil water response in the mattic epipedon layer (0–20 cm) and organic layer (20–40 cm) were 3.24 mm and 16.61 mm, respectively. The difference in the average response time of soil water to a single precipitation event between the mattic epipedon layer and organic layer was 5.52 ± 3.65 h. These results deepen the understanding of the temporal pattern of water flux in alpine meadow ecosystems on the Tibetan Plateau.

Climatic and different human influences on annual and seasonal streamflow with considering the soil water storage change in the middle reaches of the Yellow River basin, China

Recent climate change and more intensive human activities have induced significant changes in streamflow along the middle reaches of the Yellow River basin (MRYRB), which has attracted considerable attention from the scientific community. However, most previous studies have focused on changes in annual streamflow by examining data from a small number of hydrological stations and the role of the various human activities remains unclear. Here we used an extended Budyko-based framework that considered changes in soil water storage (ΔS) to determine the contributions of changes in streamflow, both at the annual and seasonal scale. These analysis were conducted on 40 catchments and three sections (Toudaoguai–Longmen, TDG–LM; Longmen-Huayuankou, LM–HYK; and Toudaoguai–Huayuankou, TDG–HYK) in the MRYRB from 1971 to 2015. Results showed that streamflow at most catchments and sections declined dramatically after years of abrupt change detected by the Pettitt test, with decreases occurring at a faster rate during flood seasons (42.9%) than during non-flood seasons (31.8%). Although human behaviors were often the main cause of streamflow reductions at the annual and seasonal scales, the effects of ΔS became more important at increasingly finer scales. Indeed, they were of equal or greater importance than human impacts in some catchments, with corresponding relative contributions up to 48%. The effects of human activities may possibly have been overestimated or underestimated by 1–16% in three sections when the impact of ΔS was not considered. Further analysis indicated that human water use – particularly the rapid increase in water withdrawals for domestic purposes, electricity generation, and manufacturing – was the primary factor among human activities that affected streamflow reduction in the LM–HYK and TDG–HYK sections at different timescales, comprising 60–90% of all impacts. By contrast, the effects of water use and other human factors were almost equal in the TDG–LM section. Among the other human factors, vegetation restoration played a more critical role in the TDG–LM section, whereas the construction of check-dams was more important in the LM–HYK section. These findings of our study can enhance the understanding of hydrological changes in response to environmental factors.

The field mulching could improve sustainability of spring maize production on the Loess Plateau

Despite field mulching has been widely adopted to improve crop productivity, agro-ecosystem sustainability of this technology in arid and semi-arid areas is inconclusive. We examined the response of yield stability, changes in soil water storage (ΔSWS), nitrogen (N) budget, soil total nitrogen (TN) content and soil organic carbon (SOC) content to furrow-ridge tillage and film or straw field mulching practices in a 6-year field experiment of rain-fed spring maize (Zea mays L.) on the Loess Plateau from 2016 to 2021. Five tillage practices included conventional tillage (CT), ridge tillage (RT), flat planting with plastic film mulching (FM), ridge tillage with plastic film mulching on ridge (RTF) and maize straw mulching (SM). Nitrogen application rates were 0 and 225 kg N ha−1. Maize yield and yield sustainability index (SYI) of plastic film mulching increased by 26.8%− 73.4% and 4.4%− 13.9%, respectively, compared with CT, and coefficient of variation (CV) of plastic film mulching declined by 0.7%− 10.7% relative to that of CT. The average ΔSWS of all tillage patterns were positive, and the rainwater use potential was 88.3–96.9%. The N budget in all practices was positive under N applied treatments but negative without N input. Without N application, N consumption was substantially exacerbated by plastic film mulching, whereas it was mitigated to some extent by SM. The TN and SOC contents were maintained under plastic film mulching. Soil TN and SOC contents in SM increased by 27.1–29.8% and 22.3–33.3%, respectively, in tested stage. However, its yield varied substantially, particularly under no N application. Small yield increase and higher CV and lower SYI occurred in RT practice. The SOC declined similar to CT. Overall, there was higher variation of yield in SM practice. The SOC appeared to decline in RT practice. The plastic film mulching was a promising practice to increase and stabilize maize yields, improve the rainfall use potential, increase or maintain the TN and SOC contents in semi-arid regions. However, attention should be paid to the impact of microplastic contamination in future research.

Paddy Field Water Movement Through Soil Profiles Under Different Water Management Practices: A HYDRUS 1D Model Study

Physical measurement of hydrological processes through soil profile is very complicated and timeconsuming. Complex and coupled physical processes like water movement with soil matric potential in puddled paddy field can be simulated using physical process-based model HYDRUS 1D. The model simulation was setup for the multilayered (different soil materials at 0-15 and 15-30 cm depth) paddy fields having continuous flooded irrigation (CFI) practice and water saving Alternate Wetting and Drying (AWD) practice. Measured soil physical properties of three Bangladesh Rice Research Institute (BRRI) regional station farms (Kushtia, Sirajganj, and Rangpur) were used as model input, initial and boundary conditions configuration. The model was calibrated and validated using the water data of a dry season field experiment in Kushtia. The calibrated (RMSE of 0.54 cm, d of 0.94, NSE of 0.89) water level data validated successfully with observed water level data of AWD practiced paddy field (d of 0.95, NSE of 0.92). Soil water content reached the threshold/critical level in AWD practice (-101 cm of water soil matric potential at 15 cm soil depth) earlier in light textured soil (loam or sandy loam) compared to heavy textured soil (clay). The physical properties of the layered soils (i.e., soil particle size distribution and soil water release curve, SWRC) did not affect much on water movement in CFI practice, but it had substantial impact on field water movement under AWD practice. The change in soil water storage followed the general trend for respective soil water holding and releasing capacity, clay soil was heavier and released water slowly than that of loam or sandy loam soils. The positive water flux above 15 cm of soil profile mainly drove the water flow due to evapotranspiration and soil water and pressure distribution along the soil profile while the negative fluxes below 15 cm of soil depth due to infiltration or percolation contributed as a secondary force. A basic understanding of HYDRUS simulated results would lead to realize the total physiohydrological environment in the paddy field. Bangladesh Rice J. 25 (2) : 57-67, 2021

Attribution of runoff variance in the alpine basin of Northwest China at multiple timescales

ABSTRACT Attributions of runoff variability have been widely conducted under the Budyko framework; however, the effects of snow water equivalent change (∆swe) have not been considered by this framework in alpine basins. Considering the Heihe upstream basin of Northwest China as an example, we derived runoff variance () from the variance and covariance of precipitation (P), soil water storage change (∆soil), ∆swe, potential evapotranspiration (E 0), and land surface condition (represented by Budyko’s parameter, n) on seasonal and annual scales. The results showed that P variance mainly controlled in autumn and winter. The n variance ranked first in spring and summer. The effects of P and n variance on annual were enhanced compared to their seasonal values. However, was alleviated by the interaction between factors, especially by ∆soil and n, P and ∆soil with negative contributions. The effects of ∆swe variance could not be ignored, especially in spring.

Water use dynamics of trees in a Pinus tabuliformis plantation in semiarid sandy regions, Northeast China

Quantifying tree water use and its environmental controlling mechanisms are significantly important for understanding of adaptation strategy of trees and plantation management in semiarid and arid regions. Here, tree water consumption and tree conductance of Chinese pine (Pinus tabuliformis) plantation were quantified using sap flow measurements. Environmental variables were measured concurrently during the growing seasons of 2019 and 2020. Results showed that daily, daytime and nighttime tree water consumption averaged 27.4, 24.7, and 2.7 kg d-1 across two years, respectively. Nighttime tree water consumption accounted for 10% of the daily’s, which was mainly used for recharging stem water storage deficit caused by daytime transpiration to avoid hydraulic failure. Daytime tree water consumption was more driven by solar radiation than by vapor pressure deficit. Moreover, daytime tree conductance was 0.9 mm s-1, and significantly decreased with increasing vapor pressure deficit and decreasing soil moisture, indicating that trees had strict stomatal regulation on tree transpiration. Scaling-up from tree to stand transpiration, daytime stand transpiration averaged 1.1 mm d-1 across two years, while accumulated stand transpiration was 112.8 mm and 126.8 mm in 2019 and 2020, respectively, accounting for 33% and 37% of precipitation. However, soil evaporation occupied 35% and 51% of precipitation in 2019 and 2020, respectively. This indicated that most of water in the plantation was consumed by soil evaporation. Difference between precipitation and sum of daytime stand transpiration, canopy interception, soil evaporation, and change in soil water storage was positive in two years, indicating that water budget was balanced. These findings indicated that Chinese pine trees had strict stomatal regulation on tree transpiration, and could recharge stem water storage deficit by nighttime sap flow. Moreover, stand transpiration occupied a small part of the water balance, and thus water supply was surplus, resulting in maintaining the stability of Chinese pine plantation.

Ammoniated straw incorporation increases wheat yield, yield stability, soil organic carbon and soil total nitrogen content

Straw management strategies are highly important for maximizing the benefits of straw incorporation, which should aim to increase crop production while improving soil fertility. Ammoniated straw incorporation may be one of the potential candidates for achieving these goals. However, the effects of ammoniated straw incorporation on wheat yield, yield stability and soil properties as well as their potential relationships remain poorly understood. Based on an ongoing long-term field experiment commenced in 2011 on the Chinese Loess Plateau, we investigated the responses of soil properties, wheat yield and yield stability of winter wheat ( Triticum aestivum L.) to ammoniated and conventional straw incorporation during 2017–2020. The three treatments were: (i) no straw (Control), (ii) conventional straw incorporation (CSI), and (iii) ammoniated straw incorporation (ASI). We found that the ASI treatment on average significantly increased wheat yield by 10.1% and yield stability by 19.5% compared to the CSI treatment, and significantly increased wheat yield by 26.9% and yield stability by 38.7% compared to the Control treatment. Changes in wheat yield and yield stability were positively related to ASI-induced increases in soil water storage. When compared to the Control and CSI treatments, the ASI treatment on average significantly increased soil organic carbon (SOC) content by 17.2% and 14.2% and total nitrogen (TN) content by 27.3% and 18.3% in 0–10 cm depth, and it significantly increased SOC content by 19.2% and 12.4% and TN content by 27.8% and 19.4% in 10–20 cm depth, respectively. There were positive relationships between changes in wheat yield and SOC and TN content. These results demonstrate that it is feasible to achieve higher wheat yield and yield stability while increasing SOC and TN content by optimizing straw management practices in semi-arid areas. • We compared ammoniated and conventional straw incorporation (ASI and CSI) for their performances in wheat cropping. • ASI treatment increased grain yield, yield stability, SOC and TN compared to CSI and Control treatments. • Increases in grain yield and yield stability are positively correlated with changes in soil water storage. • There were positive relationships between changes in grain yield and SOC and TN.

Water productivity of forage sorghum in response to winter cover crops in semi-arid irrigated conditions

Forage sorghum (Sorghum bicolor (L.) Moench) is a suitable alternative for corn silage in water-limited environments due to its similar yield potential as corn but with less water input. Cover cropping could further improve forage sorghum yield and water productivity, making it the best alternative forage crop for arid and semi-arid regions. This two-year study evaluated the effect of fallow and cover crops on soil volumetric water content (VWC), soil water extraction, changes in soil water storage (∆S), seasonal crop evapotranspiration (ETseasonal), cropping system evapotranspiration (ETsystem), seasonal crop water productivity (CWPseasonal), cropping system water productivity (CWPsystem) and forage sorghum yield under a no-till semi-arid irrigated condition. Treatments included three winter cover crop mixtures: grasses + brassicas + legumes (GBL), grasses + brassicas (GB), grasses + legumes (GL), and a no-cover crop control (fallow), arranged in a randomized complete block design with four replications. Cover crops significantly reduced soil VWC at the beginning and up to 30 days after sorghum planting (DAP). However, at 60 DAP, the VWC was mostly similar among all treatments, and at 90 DAP, it was 17–21% higher under the cover crop treatments than fallow. The ETseasonal was 22–26% higher under cover crops than fallow during cover crop growth, but it was 12–13% greater under fallow than the cover crops during forage sorghum growth. Total soil water extraction at sorghum harvest was 8–89% higher under fallow than cover crops treatments. Averaged across years, cover crop biomass yield was 11% greater with the GBL mixture than the GB and GL mixtures. Forage sorghum yield was 23%, 32%, and 18% higher under GBL, GB, and GL cover crop mixtures, respectively, than fallow. Compared to fallow, cover crop mixtures improved sorghum CWP by 38–43%. Results indicated that forage sorghum yield and CWP under semi-arid irrigated systems could be substantially improved with winter cover cropping than leaving the land fallow.

Comparison of water consumption for the conversion of croplands to orchards in dryland ecosystems

AbstractEvapotranspiration (ET) is the main ecological and soil water consumption process in terrestrial ecosystems. Previous studies have investigated ET partitioning across sites and plants; however, direct comparisons of water consumption before and after the transition from one crop to another are scarce. The variation in and proportion of ET and its subcomponents as well as the change in soil water storage (SWS) were compared in maize (Zea mays L.) croplands and apple (Malus domestica auct. non Borkh. cv. Fuji) orchards in four active (approximately May to September) and three inactive growth periods on the southern Loess Plateau, China. Soil water evaporation (Es) accounted for 36.3 and 37.7% of the total ET for cropland and orchard, respectively, in the active growth period. The canopy interception (Ic) significantly differed between cropland and orchard. The mean Ic/ET for cropland and orchard was 23.1 and 22.7%, respectively, in the active growth period, showing that the effects of Ic on ET partitioning should not be ignored. The mean ratio of transpiration (T) to ET for cropland was 2.8% less than that for orchard during the active growth period. The T/ET of cropland peaked twice in each active growth period. Precipitation (P) met the water consumption requirements of crop growth in the active growth period. The ET of cropland and orchard in the inactive growth period accounted for 29.4 and 31.8% of the ET for the hydrological year, respectively. These results help assess water consumption and soil sustainability under changes in crops in dryland agricultural ecosystems.

LONG-TERM WATER BALANCE IN SMALL CATCHMENTS IN THE ATLANTIC FOREST OF SOUTHEAST BRAZIL

The Atlantic Forest (Mata Atlântica) supplies millions of people with fresh water. Long-term studies of its catchments are essential for an understanding of the hydrological processes involved. A study of the annual water balance maintained in small catchments of the Walter Emmerich Forest Hydrology Laboratory (LHFWE), Serra do Mar State Park, Brazil, was carried out over a period of 20 years (catchment A), 26 years (catchment B) and 30 years (catchment D). The basic hydrological equation P = Q + ET ± ∆S was used. Rainfall (P) was measured with tipping bucket rain gauges installed in clearings. Streamflow (Q) was measured in gauging stations equipped with continuous stage recorders. Soil water storage change (∆S) was considered equal to zero. Evapotranspiration (ET) was calculated by the difference between P and Q. Average annual rainfall of the catchments was high with a mean of 1960 mm and wide interannual variability. The average streamflow was 1432 mm, corresponding to 73% of the rainfall, indicating remarkable water yield in the catchments. The average annual evapotranspiration was 32.2% for catchment A, 24.5% for B and 24.4% for D. These percentages are smaller than those obtained in studies carried out in other tropical forests, including the Atlantic Forest biome.

Spatial analysis of soil water depletion and biomass production in the transition zone between a Eucalyptus camaldulensis stand and a maize field in Ethiopia

Growth depressions in crops grown adjacent to Eucalyptus stands are often reported. The reasons for this observation range from competition for the resources light, nutrients and water to allelopathic effects. We investigated the effect of a Eucalyptus camaldulensis stand on soil water relations of an adjacent field of Zea mays. We used a geostatistical network spanning the Eucalyptus camaldulensis stand and the maize field. We measured changes in soil water storage in high spatial resolution (356 sample points over 3700 m²) in weekly to monthly intervals. In addition, an intensive root inventory of the Eucalyptus, covering a depth of 3.1 m, as well as aboveground biomass inventories in both land use forms were carried out. The majority of the fine root biomass of the Eucalyptus (70.5%) was found in the first 60 cm soil depth, which corresponded to the depth of the soil moisture measurements. Soil water depletion in the maize field was greatest up to 20 m from the forest edge, which coincided with the zone of least maize biomass production. In contrast, the water depletion across the first 6 m into the forest was 34% lower than in the border zone on the field side. Growth of the Eucalyptus was greatest at the forest edge, and the increased biomass production of the Eucalyptus balanced the decrease in maize production found in the first 20 m of the field. These changes in spatial growth patterns are explained by intense competition for soil water between the Eucalyptus and the maize.

A Water Balancing Act: Water Balances Highlight the Benefits of Community-Based Adaptive Management in Northern New Mexico, USA

Quantifying groundwater recharge from irrigation in water-scarce regions is critical for sustainable water management in an era of decreasing surface water deliveries and increasing reliance on groundwater pumping. Through a water balance approach, our study estimated deep percolation (DP) and characterized surface water and groundwater interactions of two flood-irrigated fields in northern New Mexico to evaluate the regional importance of irrigation-related recharge in the context of climate change. DP was estimated for each irrigation event from precipitation, irrigation input, runoff, change in soil water storage, and evapotranspiration data for both fields. Both fields exhibited positive, statistically significant relationships between DP and total water applied (TWA), where one field exhibited positive, statistically significant relationships between DP and groundwater level fluctuation (GWLF) and between GWLF and total water applied. In 2021, total DP on Field 1 was 739 mm, where 68% of irrigation water applied contributed to DP. Field 2′s total DP was 1249 mm, where 81% of irrigation water applied contributed to DP. Results from this study combined with long-term research indicate that the groundwater recharge and flexible management associated with traditional, community-based irrigation systems are the exact benefits needed for appropriate climate change adaptation.

Plastic film mulching affects field water balance components, grain yield, and water productivity of rainfed maize in the Loess Plateau, China: A synthetic analysis of multi-site observations

Plastic film mulching (PM) has been widely practiced for rainfed maize (Zea mays L.) in the Loess Plateau, China. However, controversy remains regarding its impacts on field water balance components. There is also scant quantitative information on water-limited potential grain yield (GYw) and water productivity (WPw). A meta-analysis and boundary line analysis were conducted using 1421 paired observations extracted from 83 peer-reviewed publications to (1) assess PM-induced changes in soil water storage at planting (SWSP), evapotranspiration (ET), and soil water storage at harvest (SWSH), and (2) quantify GYw and WPw in PM fields. PM significantly increased SWSP by 4.0% on average due to an 83.2% average increase in precipitation storage during the fallow season. Overall, ET showed a significant positive response to PM (+2.9%), resulting in 56.4% more soil water depletion than no-mulching (NM) fields over the growing season. However, SWSH significantly increased by an average 1.8% after applying PM, indicating that increased storage of fallow season precipitation replenished increased depletion of growing season soil water. Averaged across all samples, PM had significant positive effects on GY (+56.1%) and WP (+47.5%), which were attributed to higher transpiration, ratio of transpiration to ET, and harvest index from the perspective of effective crop water use. Based on GY and WP boundary lines, GYw and WPw under NM were estimated to be 10,728 kg ha-1 and 26.8 kg ha-1 mm-1 on average, respectively, and the respective averages under PM were 13,702 kg ha-1 and 34.8 kg ha-1 mm-1. The GY and WP gaps (i.e., differences between actual and potential values) averaged around 3300 kg ha-1 and 7.0 kg ha-1 mm-1, respectively, in NM and PM fields. In the GY versus ET and WP versus ET scatter plots, the vertical distances between the measured data points on a specific field and the corresponding boundary line indicated field-specific gaps for GY and WP. This study increases our understanding of the effect sizes of PM on field water balance components and the benchmarks of GY and WP for rainfed maize in the Chinese Loess Plateau and other regions with similar conditions worldwide.