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Abstract. Livestock manure nitrogen (N) and phosphorus (P) play an importantrole in biogeochemical cycling. Accurate estimation of manure nutrient isimportant for assessing regional nutrient balance, greenhouse gas emission,and water environmental risk. Currently, spatially explicit manure nutrientdatasets over a century-long period are scarce in the United States (US).Here, we developed four datasets of annual animal manure N and P productionand application in the contiguous US at a 30 arcsec resolution overthe period of 1860–2017. The dataset combined multiple data sourcesincluding county-level inventory data as well as high-resolution livestockand crop maps. The total production of manure N and P increased from 1.4 Tg N yr−1 and 0.3 Tg P yr−1 in 1860 to 7.4 Tg N yr−1 and 2.3 Tg P yr−1 in 2017, respectively. The increasing manure nutrient productionwas associated with increased livestock numbers before the 1980s andenhanced livestock weights after the 1980s. The manure application amountwas primarily dominated by production, and its spatial pattern was impactedby the nutrient demand of crops. The intense-application region mainlyenlarged from the Midwest toward the southern US and became moreconcentrated in numerous hot spots after the 1980s. The South Atlantic–Gulf and Mid-Atlantic basins were exposed to high environmental risks due to theenrichment of manure nutrient production and application from the 1970s tothe period of 2000–2017. Our long-term manure N and P datasets providedetailed information for national and regional assessments of nutrientbudgets. Additionally, the datasets can serve as the input data forecosystem and hydrological models to examine biogeochemical cycles interrestrial and aquatic ecosystems. Datasets are available at https://doi.org/10.1594/PANGAEA.919937 (Bian etal., 2020). 

Abstract. Water management substantially alters natural regimes ofstreamflow through modifying retention time and water exchanges amongdifferent components of the terrestrial water cycle. Accurate simulation ofwater cycling in intensively managed watersheds, such as the Yakima River basin (YRB) in the Pacific Northwest of the US, faces challenges inreliably characterizing influences of management practices (e.g., reservoiroperation and cropland irrigation) on the watershed hydrology. Using the Soiland Water Assessment Tool (SWAT) model, we evaluated streamflow simulationsin the YRB based on different reservoir operation and irrigation schemes.Simulated streamflow with the reservoir operation scheme optimized by theRiverWare model better reproduced measured streamflow than the simulationusing the default SWAT reservoir operation scheme. Scenarios with irrigationpractices demonstrated higher water losses through evapotranspiration (ET)and matched benchmark data better than the scenario that only consideredreservoir operations. Results of this study highlight the importance ofreliably representing reservoir operations and irrigation management forcredible modeling of watershed hydrology. The methods and findings presentedhere hold promise toenhance water resources assessment that can be applied to other intensively managed watersheds.