Wet Water Year Research Articles

Estimating spatiotemporally continuous snow water equivalent from intermittent satellite observations: an evaluation using synthetic data

Abstract. Accurate estimates of snow water equivalent (SWE) based on remote sensing have been elusive, particularly in mountain areas. However, there now appears to be some potential for direct satellite-based SWE observations along ground tracks that only cover a portion of a spatial domain (e.g., watershed). Fortunately, spatiotemporally continuous meteorological and surface variables could be leveraged to infer SWE in the gaps between satellite ground tracks. Here, we evaluate statistical and machine learning (ML) approaches to performing track-to-area (TTA) transformations of SWE observations in California's upper Tuolumne River watershed using synthetic data. The synthetic SWE measurements are designed to mimic a potential future P-band Signals of Opportunity (P-SoOP) satellite mission with a (along-track) spatial resolution of about 500 m. We construct relationships between multiple meteorological and surface variables and synthetic SWE observations along observation tracks, and we then extend these relationships to unobserved areas between ground tracks to estimate SWE over the entire watershed. Domain-wide, SWE inferred on 1 April using two synthetic satellite tracks (∼4.5 % basin coverage) led to percent errors of basin-averaged SWE (PEBAS) of 24.5 %, 4.5 % and 6.3 % in an extremely dry water year (WY2015), a normal water year (WY2008) and an extraordinarily wet water year (WY2017), respectively. Assuming a 10 d overpass interval, percent errors of basin-averaged SWE during both snow accumulation and snowmelt seasons were mostly less than 10 %. We employ a feature sensitivity analysis to overcome the black-box nature of ML methods and increase the explainability of the ML results. Our feature sensitivity analysis shows that precipitation is the dominant variable controlling the TTA SWE estimation, followed by net long-wave radiation (NetLong). We find that a modest increase in the accuracy of SWE estimation occurs when more than two ground tracks are leveraged. The accuracy of 1 April SWE estimation is only modestly improved for track repeats more often than about 15 d.

Spatial variability and temporal stability of actual evapotranspiration on a hillslope of the Chinese Loess Plateau

Actual evapotranspiration (ETa) is a key component of water balance. This study aimed to investigate the spatial variability and time stability of ETa along a hillslope and to analyze the key factors that control the spatiotemporal variability of ETa. The potential evaporation, surface runoff, and 0–480 cm soil water profile were measured along a 243 m long transect on a hillslope of the Loess Plateau during the normal (2015) and wet (2016) water years. ETa was calculated using water balance equation. Results indicated that increasing precipitation during the wet water year did not alter the spatial pattern of ETa along the hillslope; time stability analysis showed that a location with high time stability of ETa could be used to estimate the mean ETa of the hillslope. Time stability of ETa was positively correlated with elevation (P<0.05), indicating that, on a hillslope in a semi-arid area, elevation was the primary factor influencing the time stability of ETa.

Large‐Scale Flow Management Action Drives Estuarine Ecological Response

AbstractResource managers rely on large‐scale flow and habitat enhancement actions to support sensitive species in the San Francisco Bay–Delta. The effects of these actions on target species and ecosystems are largely unknown. In 2018, we implemented an ecosystem‐scale experiment to reduce salinity and improve access to high‐quality habitat in Suisun Marsh, California, for Endangered Species Act‐listed Delta Smelt Hypomesus transpacificus. The action included a release of approximately 46 million m3 of additional flow in conjunction with the operation of a novel water management facility, the Suisun Marsh Salinity Control Gates. This experimental action resulted in more low‐salinity habitat in Suisun Marsh than would have been present as compared to similar historical low‐flow summer conditions. We evaluated the effect of decreasing salinity on the species assemblage in Suisun Marsh using a combination of ordination analyses and circular statistics. We focused this analysis on long‐term monitoring data collected within Suisun Marsh during July and August and found that the aquatic community changed significantly in small sloughs but not large‐slough habitat in response to the Suisun Marsh action. The assemblage shift from July to August 2018 differed from historical trends in both slough sizes, albeit not significantly in large‐slough habitat. Specifically, we observed (1) a shift in California bay shrimp Crangon franciscorum and Striped Bass Morone saxatilis abundance like that occurring in low‐salinity, wet water year types; and (2) an uncharacteristic seasonal decline in Black Sea jellyfish Maeotias marginata. We posit that the observed community changes were driven by a combination of behavioral responses to lower‐salinity conditions and physical displacement by directional flow resulting from the flow management action.

Interaction of restored hydrological connectivity and herbicide suppresses dominance of a floodplain invasive species

Invasive species present one of the largest threats to the recruitment and persistence of native plant communities. Land managers generally apply two approaches to help control invasive species and restore native plant communities: (1) improve ecosystem processes that preferentially support native species (e.g. reintroduce disturbance regimes) or (2) directly treat non‐native species (e.g. herbicide use). Few utilize both. Over nearly a decade, we tracked the establishment and population growth of Lepidium latifolium (perennial pepperweed) on a hydrologically restored floodplain and adjacent grassland sites, concurrently with a controlled herbicide application experiment. We found that perennial pepperweed stem counts were lower in years with longer duration flood events (p &lt; 0.0001) and after herbicide application (p &lt; 0.0005). In floodplain areas, native species increased in the years following herbicide treatments or after wet water years, while grassland sites were reinvaded by other non‐native species. Our results suggest that long inundation periods can effectively control perennial pepperweed over large areas when used in concert with herbicide control during dry years or in drier areas. Given the natural variability in inundation periods, our study highlights the need for longer‐term (&gt;3–5 years) studies to evaluate the effectiveness of invasive species control programs. Overall, our study emphasized the need for further integration of traditional weed control approaches with restored ecological function to effectively control invasive plants and stimulate native plant recovery.

Analisis Pengisian Awal (Impounding) pada Bendungan Raknamo Dengan Model Tangki

The impounding of the dam is the step that will be done after construction work on the dam be finished. This study aims to determine a long time and the volume of inflow on Raknamo dam in dry water year, low water year, normal water year and wet water year with tank model. Factors that affected the time of the first impounding of the dam is the amount of rainfall and evapotranspiration that has come in to the catchment area. The total volume of annual inflow Raknamo reservoir obtained in dry water year was in 15,489 million m3, low water year equal to 23,696 million m3, normal water year equal to 32,892 million m3 and wet water year equal to 44,068 million m3. In the calculation of the length of time filling the Raknamo reservoir used the volume of low water year. The accumulation of the volume of every month calculated so that length of time filling the Raknamo reservoir can reach the volume of planned at 14.091 million m3 within three a half months (three months fifteen days).

Watersheds dynamics following wildfires: Nonlinear feedbacks and implications on hydrologic responses

AbstractIn recent years, wildfires in the western United States have occurred with increasing frequency and scale. Climate change scenarios in California predict prolonged periods of droughts with even greater potential for conditions amenable to wildfires. The Sierra Nevada Mountains provide 70% of water resources in California, yet how wildfires will impact watershed‐scale hydrology is highly uncertain. In this work, we assess the impacts of wildfires perturbations on watershed hydrodynamics using a physically based integrated hydrologic model in a high‐performance‐computing framework. A representative Californian watershed, the Cosumnes River, is used to demonstrate how postwildfire conditions impact the water and energy balance. Results from the high‐resolution model show counterintuitive feedbacks that occur following a wildfire and allow us to identify the regions most sensitive to wildfires conditions, as well as the hydrologic processes that are most affected. For example, whereas evapotranspiration generally decreases in the postfire simulations, some regions experience an increase due to changes in surface water run‐off patterns in and near burn scars. Postfire conditions also yield greater winter snowpack and subsequently greater summer run‐off as well as groundwater storage in the postfire simulations. Comparisons between dry and wet water years show that climate is the main factor controlling the timing at which some hydrologic processes occur (such as snow accumulation) whereas postwildfire changes to other metrics (such as streamflow) show seasonally dependent impacts primarily due to the timing of snowmelt, illustrative of the integrative nature of hydrologic processes across the Sierra Nevada‐Central Valley interface.

Applying a simplified energy-budget model to explore the effects of temperature and food availability on the life history of green sturgeon (Acipenser medirostris)

In highly regulated systems, like large dammed rivers, conservation legislation requires that systems are managed, in part, to avoid adverse impacts on endangered species. However, multiple endangered species can occur in the same system, and management actions that benefit one species may be detrimental to another species. The current water management strategies in the Sacramento River basin are an example of this conflict. Cold-water releases from Shasta Reservoir during the summer and fall months are aimed at protecting Sacramento River winter-run Chinook (SRWRC) salmon by providing suitable incubation temperatures for their eggs. However, the effects of these regulated water temperature releases on another threatened species, green sturgeon, are less well understood. In this study, we applied a simplified dynamic energy budget (DEB) model (aka DEBkiss) to explore the effect of food limitation and water temperature on the growth rates of green sturgeon. This model captures these effects and able to predict the growth of green sturgeon at different food levels and temperature conditions. We then linked the DEB model with a physically‐based water temperature model. We applied the DEB - water temperature linked model for green sturgeon along with a temperature-dependent egg to fry survival model for SRWRC salmon to quantify the consequences of managing water temperatures to improve salmon eggs survival on the growth rate of green sturgeon. We found that mean temperature-dependent egg-to-fry survival of salmon increased across a modeled environmental gradient from critically dry to wet water year types, while the fractional growth rate of juvenile green sturgeon showed the opposite trend, and decreased as water years transitioned from dry to wet conditions. We also found a non-linear negative correlation between temperature-dependent mean growth rate of green sturgeon and mean temperature-dependent egg-to-fry survival of salmon, which indicated there is a river temperature related trade-off between early growth rate of green sturgeon and embryonic stage survival of salmon. However, the relatively small gains in the growth rate of green sturgeon achieved in years when temperature criteria for SRWRC salmon eggs were not met came at the cost of large reduction in temperature-dependent egg-to-fry survival of salmon. Thus, we concluded the current Sacramento River water-temperature management for the eggs of the endangered SRWRC salmon eggs have a relatively small impact on the growth rate of green sturgeon.

Reservoir volume optimization and performance evaluation of rooftop catchment systems in arid regions: A case study of Birjand, Iran

This study evaluated the performance of rooftop catchment systems in securing non-potable water supply in Birjand, located in an arid area in southeastern Iran. The rooftop catchment systems at seven study sites of different residential buildings were simulated for dry, normal, and wet water years, using 31-year rainfall records. The trial and error approach and mass diagram method were employed to optimize the volume of reservoirs in five different operation scenarios. Results showed that, during the dry water year from 2000 to 2001, for reservoirs with volumes of 200–20000 L, the proportion of days that could be secured for non-portable water supply was on average computed to be 16.4%–32.6% across all study sites. During the normal water year from 2009 to 2010 and the wet water year from 1995 to 1996, for reservoirs with volumes of 200–20000 L, the proportions were 20.8%–69.6% and 26.8%–80.3%, respectively. Therefore, a rooftop catchment system showed a high potential to meet a significant portion of non-potable water demand in the Birjand climatic region. Reservoir volume optimization using the mass diagram method produced results consistent with those obtained with the trial and error approach, except at sites #1, #2, and #5. At these sites, the trial and error approach performed better than the mass diagram method due to relatively high water consumption. It is concluded that the rooftop catchment system is applicable under the same climatic conditions as the study area, and it can be used as a drought mitigation strategy as well.

Provide management package in irrigation networks to achieve optimal performance measures

Saving water and improving water productivity influence the socioeconomic measures like equity that should be considered in water distribution management especially in drought conditions. In this research for different scenarios of irrigation water management, the performance measures of water equity and productivity in Ordibehesht channel (Doroodzan irrigation network) was optimised simultaneously by using genetic algorithm (GA). The results showed that rising water reduction fraction (WRF) (0.0 to 0.8) has the incremental effect on water equity and productivity (on average 39.2% and 43.3%, respectively). With increasing irrigation application efficiency (Ea) (40% to 90%), the values of water equity and productivity increased by on average 59.9% and 113.5%, respectively. Increment of conveyance efficiency of channels (Ec) (70% to 90%) resulted in minimum incremental effect on water equity and productivity (on average 19.8% and 14.1%, respectively). Furthermore, the values of performance measure decreased from wet water year to drought water year.

黄河下游冲淤平衡的临界输沙量研究

本文分析了三门峡水库和小浪底水库不同运用时期黄河下游冲淤特征，在总结分析前人有关黄河下游冲淤平衡时的不同含沙量的临界流量成果的基础上，利用花园口、高村水文站逐日水沙资料，通过年径流量大小划分不同水文年，选择不同水文年典型代表年分别为平水年(1976~1978年)、丰水年(1982~1985年)和枯水年(1986~1988年)，利用总结的估算方法，推算出不同水文年黄河下游水沙冲淤平衡的临界输沙量为平水年6.54亿t、丰水年8.83亿t和枯水年3.95亿t，平均值为6.44亿t。研究结果可为黄河下游河道治理提供科学依据。 The characteristics of scour and deposition of Sanmenxia reservoir and Xiaolangdi reservoir different application period in the lower reaches were analyzed. Based on previous researches on critical flow of different sediment concentration under equilibrium between scouring and deposition in the lower reaches of the Yellow River, using daily flow of Huayuankou and Gaocun hydrologic station, different hydrological years are divided by annual runoff; the typical representative years of different hydrological years are normal water year (from 1976 to 1978), wet water year (from 1982 to 1985) and dry year (from 1986 to 1988). The critical sediment discharges of different hydrologic years were calculated using a summary of the estimation methods. The lower reaches of Yellow River is in equilibrium between scouring and deposition, which is 6.54 × 108 t, 8.83 × 108 t and 3.95 × 108 t in normal year, wet year and dry year respectively, with an average of 6.44 × 108 t. It provides scientific basis for the lower reaches regulation of the Yellow River.

Effect of Various On-Farm Water Management Scenarios on Equity and Productivity in Irrigation Networks

This research investigated the optimum on-farm water management methods for a summer crop (Maize). Water equity and productivity were optimized simultaneously by using genetic algorithms in Doroodzan Irrigation Network. Increase in water reduction fraction (WRF) (0.0 to 0.8) has the incremental effect on water equity (on average 19.4 %), however by increasing WRF, water productivity initially increased (on average 25.3 % at WRF = 0.4) and then decreased. With increasing irrigation application efficiency (Ea) (40 to 90 %), the values of water equity and productivity increased by on average 52.8 and 91.5 %, respectively. Increment of conveyance efficiency of channels (Ec) (70 to 90 %) resulted in minimum incremental effect on water equity and productivity (on average 18.5 and 11.9 %, respectively). Furthermore, the values of performance measure decreased from wet water year to drought water year. Tape irrigation system was considered as the best choice at low quantities of WRF ( = 0.6), sprinkler irrigation system was considered as the best choice for achieving higher values of water equity and productivity. Meanwhile, when equity and productivity were considered together for a specific method of deficit irrigation scheduling, under specified quantity of irrigation water, with increasing equity the water productivity reduction was negligible.

A framework to identify Pareto‐efficient subdaily environmental flow constraints on hydropower reservoirs using a grid‐wide power dispatch model

AbstractHydrologic alteration due to hydropeaking reservoir operations is a main concern worldwide. Subdaily environmental flow constraints (ECs) on operations can be promising alternatives for mitigating negative impacts. However, those constraints reduce the flexibility of hydropower plants, potentially with higher costs for the power system. To study the economic and environmental efficiency of ECs, this work proposes a novel framework comprising four steps: (i) assessment of the current subdaily hydrologic alteration; (ii) formulation and implementation of a short‐term, grid‐wide hydrothermal coordination model; (iii) design of ECs in the form of maximum ramping rates (MRRs) and minimum flows (MIFs) for selected hydropower reservoirs; and (iv) identification of Pareto‐efficient solutions in terms of grid‐wide costs and the Richard‐Baker flashiness index for subdaily hydrologic alteration (SDHA). The framework was applied to Chile's main power grid, assessing 25 EC cases, involving five MIFs and five MRRs. Each case was run for a dry, normal, and wet water year type. Three Pareto‐efficient ECs are found, with remarkably small cost increase below 2% and a SDHA improvement between 28% and 90%. While the case involving the highest MIF worsens the flashiness of another basin, the other two have no negative effect on other basins and can be recommended for implementation.

First documented spawning and associated habitat conditions for green sturgeon in the Feather River, California

California’s Sacramento River mainstem was previously the only known spawning area for the Southern Distinct Population Segment of North American green sturgeon, Acipenser medirostris. Our study provides the first documentation of green sturgeon spawning in the Feather River, a major tributary of the Sacramento River. Egg mats were used to sample two lower Feather River sites from April 12 to July 7, 2011, and we collected 13 green sturgeon eggs at one of those sites. Developmental stages of the eggs ranged from early gastrulation (Stage 15) to post-neurulation (Stage 27), which led us to estimate that four independent spawning events occurred between June 12 and June 19. Spawning occurred after a flow increase while water temperatures were at an optimum (<17.5 °C) for eggs. Results suggest that the area near Thermalito Afterbay Outlet may be important green sturgeon spawning habitat and that the lower Feather River has the potential to provide a second production area of Southern Distinct Population Segment green sturgeon. It should be noted that 2011 was a wet water year and supplemental sampling is needed to understand if water-year type affects green sturgeon usage of the lower Feather River. Given this new information, future management decisions and water management strategies for the Feather River system should take green sturgeon life-history needs into consideration.

Implications of climate-driven variability and trends for the hydrologic assessment of the Reynolds Creek Experimental Watershed, Idaho

Summary The Soil and Water Assessment Tool (SWAT) model was used to assess the implications of long-term climate trends for the hydroclimatology of the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains, Idaho of the Intermountain West over a 40-year period (1967–2006). Calibration and validation of the macroscale hydrology model in this highly monitored watershed is key to address the watershed processes that are vulnerable to both natural climate variability and climate change. The model was calibrated using the streamflow data collected between 1997 and 2006 from the three nested weirs, the Reynolds Mountain East (RME), Tollgate and Outlet. For assessing the performance of the calibrated model, this study used 30 years of streamflow data for the period between 1966 and 1996. This investigation suggested that the model predicted streamflow was best at RME, and inadequate at Outlet. Simulated soil moisture was also verified using the data available from five soil moisture measurement sites. The model was able to capture the seasonal patterns of changes in soil water storage considering the differences in the spatial extent of the observed and predicted soil water storage (point measurements against the spatially averaged values for the HRU) and uncertainty associated with the soil moisture measurements due to instrument effects. Water budget partitioning during a wet (1984) water year and a dry (1987) water year were also analyzed to characterize the differences in hydrologic cycles during the extreme hydrologic conditions. Our analysis showed that in the dry water year, vegetation at the higher elevation were under water stress by the end of the water year. Contrastingly, in the wet water year only the vegetation at low and mid-elevations were under water stress whereas vegetation at the higher elevations derived substantial soil moisture for ET processes even towards the end of the growing season. To understand the effect of climate change on the hydrologic cycle, the observed and simulated streamflow were analyzed for trends in Center of Timing (CT). Earlier CT timings for the simulated and observed streamflow at RME weir was obvious thus manifesting global warming signals at the watershed scale level in the Intermountain west region. Observed streamflow at the Tollgate and Outlet weirs, where streamflow is partially affected by the agricultural diversions, showed later CT timings and these results appeared to suggest that climate impact assessment studies need to carefully distinguish the system behavior that is altered by both natural and human-induced changes.

HYDROMETEOROLOGICAL CONDITION SOVER MUJIB BASIN, JORDAN

The (P.E.) values reveal a similar seasonal variation .for six selected climatological stations 6yr)rMujib basin' The average annual values ranges between 2200 mm in the SE region to 1400 mm firrthe NW and SW regions of the basin. The relation between the long-te.- uvirug" values and tl eclimatic parameters (Class A p*, Temperature; Wind, Sun Shine duration % RH %) for thn eclimatological stations were determined using the linear regression equations. High correlatic ncoefficient values suggest that the obtained equations are highly reliable. Mujib basin is divided in, othree climatic zones : Moisture index &gt; -80 where the water balance for this zone show, yy4[r)rsurplus during Dec. to Feb. and water &lt;ieiicit during March to November. Moisture indexes ranf ebetween -80 to -90 where the water balance for the normal and wet water years show water surpli.sin lt il zone during the wetted months. Moisture index &lt; -90 where the water deficit is experience din high degree and no water surplus has been observed.

Maps of regional evapotranspiration and runoff/precipitation ratios in the northeast United States

Regional maps of evapotranspiration ( ET) and runoff/precipitation ratios ( R P ) are rare for the United States. We have found mapping of ET and R P to be a useful part of our work on runoff mapping, which in turn was a necessary part of our assessments of effects of acidic deposition. Maps of ET and R P could be useful in other water resource analyses as well. Toward this end we present maps of these variables that we have prepared for the northeastern United States. We compute ET and R P from the water balance equation with measured runoff and precipitation and (in one case) modeled estimates of precipitation. We have mapped ET and R P in three different ways. First, we have mapped them by Major Land-Use Resource Areas (MLRA). We have performed this mapping for both a long-term period (1951–1980) and an especially wet water year, water-year 1984 (WY84). Second, we have mapped ET and R P using an automated contouring procedure in association with modeled estimates of precipitation from PRISM (Precipitation-elevation Regressions on Independent Slopes Model). Third, we have manually contoured the variables based on measured values of runoff and precipitation as they appear to relate to elevation, land use, and vegetation. Our maps compare well with each other and with the relatively few prior efforts at such mapping for the region. Our findings indicate that ET tends to be much more conservative over time than R P , which tended to be greater in the wet year (WY84). As would be expected, the three approaches have relative strengths and weaknesses. Mapping by MLRA may be more useful when measured estimates are few or when lack of local expertise limits contouring subjectively. Contouring allows for more detailed representation of patterns. Automated contouring has the advantages of efficiency and reproducibility, whereas manual contouring allows the exercise of potentially more accurate expert local knowledge, when it exists.