#Daily rainfall totals series

Within the catchment, we performed a seasonal study on six streams with distinct geologies (two each on the clay, Greensand and Chalk) and over a wide spectrum of hydrological characteristics, e.g., flashy to stable hydrograph, hydrological connectivity to the land and in-stream carbon metabolism (see Heppell et al., 2017 Rovelli et al., 2017Rovelli et al.,, 2018. The aim of this study was to characterize how discharge and in-stream carbon metabolism together exert biophysical controls on the sources and final fates of CO 2 and CH 4 in temperate, low-gradient headwater streams (maximum catchment area of ∼60 km 2 ) in our case study catchment of the lowland Hampshire River Avon, UK. We developed a multiple regression model that could explain 82% of the variance in EF based on water temperature and the ratio between dissolved organic carbon and nitrate-nitrogen (p < 0.001), which could be used to improve the estimate of EF for assessing N2O emission from coastal reservoirs and other similar environments. Overall, our derived EF deviated considerably from the IPCC default value, which implied that the use of default EF could result in over- or under-estimation of N2O emissions by up to 42%. Across all the water bodies, the mean EF in summer was 1.8–3.5 and 1.7–2.8 fold higher than that in autumn and spring, respectively, owing to the elevated water temperature. The average EF varied significantly among the four types of water bodies in the following descending order: aquaculture ponds > river > drainage channels > reservoir. The empirically derived EF (calculated as N2O–N:NO3−-N) for the reservoir showed considerable spatial variations, with a 10-fold difference ranging from 0.8 × 10−3 to 8.8 × 10−3. In this study, we conducted high spatial resolution sampling of dissolved N2O, nitrate-nitrogen (NO3−–N) and other physico-chemical properties of surface water in Wenwusha Reservoir and other types of water bodies (river, drainage channels, and aquaculture ponds) in its catchment areas in southeastern China between November 2018 and June 2019. Since urbanized coastal reservoirs receive high nitrogen loads from diverse sources across a heterogeneous landscape, the use of a single fixed EF may lead to large errors in N2O assessment. While Asia is projected to be one of the major nitrous oxide (N2O) sources in the coming decades, a more accurate assessment of N2O budget has been hampered by low data resolution and poorly constrained emission factor (EF). By March 2015, warmer weather, combined with lower- than-average rainfall (< 50 % of long-term average), caused SMD to steadily increase until the end of the study period in June. SMD reached peak values of 129 mm by the end of the summer in early October 2014, and autumn rainfall during October and November caused wetting-up of the soil to reduce SMD to 0 mm by mid-November 2014. SMD and rain- fall patterns in 2014 were not as extreme as those in 2013, returning to monthly values that were much closer to the long-term averages. January 2014, in particular, was the equal wettest on record since 1910. A total of 161 mm rain fell in December 2013 (190 % of the 1961-1990 long-term av- erage), with a maximum daily rainfall total of 58 mm on 23 December, followed by a further monthly total of 205 and 148 mm in January and February 2014, 261 and 259 % of the long-term averages, respectively.

#Daily rainfall totals series

After a brief return to dry, set- tled conditions, a series of deep Atlantic low-pressure sys- tems brought a prolonged period of heavy rain to the en- tire Hampshire Avon catchment. A period of unsettled weather in October and November 2013 (224 mm rainfall in total) reduced the SMD to 0 mm. C for a 10-12 day period in July) over the summer of 2013, SMD reached a maximum of 140 mm for a 4-week period in August and September 2013.50 % of 1910-2015 long- term average for the region) and high temperatures (> 28 Due to a combination of lower-than-average rainfall (ca. first year of study (June 2013(June -2014), on which these re- sults are focused, was characterized by pronounced cycles of soil wetting and drying due to alternating periods of un- usually wet and dry weather (Fig.