Trends In Discharge Research Articles

Freshwater discharge from the large and coastal peninsular rivers of India: Areassessment for sustainable water management.

This study offers an updated mean annual water discharge of 10 large and 11 coastal basins of the Indian Peninsula and looks into environmental parameters influencing the water flux and discharge trends. The mean annual discharge of large and coastal rivers is estimated to be 221 and 294 km3. Thus, despite draining 25% of the Indian Peninsula, coastal rivers deliver more than half of the annual flux, and west-flowing coastal rivers contribute 85% of it. This study demonstrates temporal changes in the water discharge of various river basins. The presence of dams regulates discharge regimes of large rivers. The construction of large dams resulted in a significant decline in the water discharge of the Krishna, Cauvery, and Narmada. Through this study, we demonstrate the role of rainfall, catchment size, water loss through evapotranspiration and infiltration, and societal use of water in determining the runoff of each basin. We recommend tapping the water resources of the west-flowing rivers for proper planning, development, and management to reduce the water stress in the peninsular region and promoting sustainable management.

Evaluating suspended sediment and turbidity reduction projects in a glacially conditioned catchment through dynamic regression and fluvial process‐based modelling

AbstractElevated turbidity (Tn) and suspended sediment concentrations (SSC) during and following flood events can degrade water supply quality and aquatic ecosystem integrity. Streams draining glacially conditioned mountainous terrain, such as those in the Catskill Mountains of New York State, are particularly susceptible to high levels of Tn and SSC sourced from erosional contact with glacial‐related sediment. This study forwards a novel approach to evaluate the effectiveness of stream restoration best management practices (BMPs) meant to reduce stream Tn and SSC, and demonstrates the approach within the Stony Clove sub‐basin of the Catskills, a water supply source for New York City. The proposed approach is designed to isolate BMP effects from natural trends in Tn and SSC caused by trends in discharge and shifts in average Tn or SSC per unit discharge (Q) following large flood events. We develop Dynamic Linear Models (DLMs) to quantify how Tn‐Q and SSC‐Q relationships change over time at monitoring stations upstream and downstream of BMPs within the Stony Clove and in three other sub‐basins without BMPs, providing observational evidence of BMP effectiveness. A process‐based model, the River Erosion Model, is then developed to simulate natural, hydrology‐driven SSC‐Q dynamics in the Stony Clove sub‐basin (absent of BMP effects). We use DLMs to compare the modelled and observed SSC‐Q dynamics and isolate the influence of the BMPs. Results suggest that observed reductions in SSC and Tn in the Stony Clove sub‐basin have been driven by a combination of declining streamflow and the installed BMPs, confirming the utility of the BMPs for the monitored hydrologic conditions.

Effect of Discharge on Water Quality in Euphrates River Between Hit and Ramadi, Iraq

The objective of this study was to determine the relationship between water drainage rates in Hit and Ramadi cities and the water quality of the Euphrates River. The studied area of Euphrates River extends from Hit to Ramadi, where two sampling stations were selected monthly in 2012, 2013, and 2018. The results indicate variations and decreasing in the monthly discharge rate of the study period; the year 2012 had higher discharge rate values than 2013, which in turn was higher than in 2018, for both gauging stations. Our results indicate that with decreasing discharge trends, some selected water quality parameters had an increasing trend. During the selected years, there was an increase in levels of sulfate, nitrate, dissolved oxygen, magnesium, and turbidity in the Ramadi station compared to the Hit station, as the rate of discharge of the river increases in the former. A positive significant correlation between discharge rate and dissolved oxygen and dissolved solids were reported. The Haditha Dam and its reservoir affect the downstream discharge rate and in turn the water quality at Hit and Ramadi Cities.

Assessing the impact of climate on annual and seasonal discharges at the Sremska Mitrovica station on the Sava River, Serbia

Abstract Flood frequency analysis was performed on annual maxima series for 90 years (1928–2017) of discharge data recorded at the Sremska Mitrovica gauging station on the Sava River. The three-parameter distributions (PearsonIII, Log-PearsonIII) are more suitable for modelling annual maxima than distribution functions with only two parameters (Normal, Log-normal, Gumbel). The Mann–Kendall test statistic indicated that there is no statistically significant trend identified in annual maximum discharges or average annual discharges. A positive increasing trend was observed in annual temperature, while annual precipitation shows a decreasing trend which is non-significant. The seasonality analysis found a statistically non-significant weak negative trend in discharge in spring, summer and autumn and a statistically non-significant weak positive trend in winter. During winter, spring, and summer a non-significant negative trend in precipitation was observed, while autumn has experienced a statistically significant increasing trend. Temperatures show a positive trend in all seasons, but only temperatures during the warm period show a statistically significant increase. The results demonstrate that decreasing discharges of the Sava River at the Sremska Mitrovica gauging station are mainly the consequence of decreasing precipitation and increasing temperature (increasing evaporation), which is consistent with the results of other studies of the region.

A comparative study of biota and sediments as monitors of plutonium in the Yenisei River (Siberia, Russia)

MOX-fuel production and spent nuclear fuel reprocessing started recently at the Mining-and-Chemical Combine (MCC, Zheleznogorsk, Russia) have caused an increase in controlled releases of plutonium to the Yenisei River. In this study, we analyzed time-dependent trends of plutonium (239,240Pu and 238Pu) in biota and bottom sediments of the Yenisei during 2008–2019, to estimate comparatively the potential of abundant representatives of biota as bio-monitors of contamination of the Yenisei by plutonium. Gamma-emitting radionuclides (40 K; 60Co; 137Cs; 152Eu; 241Am) were measured in environmental samples of the Yenisei as well. Samples of bottom sediments, water moss (Fontinalis antipyretica), shining pondweed (Potamogeton lucens), caddisfly larvae with casings (Apatania crymophila), and amphipods (Eulimnogammarus viridis and Palaseopsis cancelloides) were collected downstream and upstream of the radioactive discharge site. Environmental samples of the Yenisei collected downstream of the radioactive discharge site differed considerably in activity concentrations of plutonium but were similar in time-dependent trends of plutonium, reflecting the trends of annual discharges of plutonium. In 2018, the year of a sharp increase in controlled discharge of plutonium, the concentration of 239,240Pu in water moss (26 Bq kg−1 d.w.) was higher than in sediments (14 Bq kg−1 d.w.). In other years, the highest activity concentration of 2391,240Pu was observed in bottom sediments. In view of the higher magnitude of increase in plutonium concentration, water moss and shining pondweed can be considered as more sensitive indicators of increased fresh releases of plutonium than bottom sediments. Taking into account the food-related mechanism of plutonium uptake by amphipods, this representative of biota can be regarded as a sensitive monitor of bioavailable plutonium in the Yenisei.

Early Discharge After Minimally Invasive Aortic and Mitral Valve Surgery

BackgroundWe investigated patient outcomes in relation to their postoperative length of stay after minimally invasive valve surgery. MethodsAll adults who survived elective, uncomplicated minimally invasive aortic or mitral valve surgery at a single center between 2012 and 2019 were classified by postoperative length of stay: early discharge (≤3 days) or late discharge (>3 days). The trend in early discharge was investigated over the study period, predictors of early discharge were identified using multivariate logistic regression modeling, and 1:1 propensity score matching was used to determine which patients in the late-discharge cohort had similar health to patients discharged early. Adjusted outcomes of 30-day mortality, readmission, and direct costs were analyzed. ResultsAmong 1262 consecutive patients undergoing minimally invasive valve surgery, 618 were elective and uncomplicated, 25% (n = 162) of whom were discharged early. The proportion of early-discharge patients increased over time (P for trend < .05). A history of congestive heart failure, stroke, or smoking and higher Society of Thoracic Surgeons predictive risk of mortality score negatively predicted early discharge (P < .05). Propensity score matching identified 101 (22%) late-discharge patients comparable with early-discharge patients. Adjusted 30-day mortality and readmission rates were comparable between cohorts. The median direct costs per patient ($20,046 vs $22,124, P < .05) were significantly lower in the early-discharge cohort. ConclusionsIn well-selected patients early discharge after minimally invasive valve surgery was associated with lower costs but comparable postoperative outcomes. About one-fifth of patients who remain in the hospital beyond postoperative day 3 may be candidates for earlier discharge.

Trends in Use and Outcomes of Same-Day Discharge Following Elective Percutaneous Coronary Intervention.

The aims of this study were to describe trends and hospital variation in same-day discharge following elective percutaneous coronary intervention (PCI) and to evaluate the association between trends in same-day discharge and patient outcomes. Insights on contemporary use of same-day discharge following elective PCI are limited. In a sequential cross-sectional analysis of 819,091 patients undergoing elective PCI at 1,716 hospitals in the National Cardiovascular Data Registry CathPCI Registry from July 1, 2009, to December 31, 2017, overall and hospital-level trends in same-day discharge were assessed. Among the 212,369 patients who linked to Centers for Medicare and Medicaid Services data, the association between same-day discharge and 30-day mortality and rehospitalization was assessed. A total of 114,461 patients (14.0%) were discharged the same day as PCI. The proportion of patients with same-day discharge increased from 4.5% in the third quarter of 2009 to 28.6% in the fourth quarter of 2017. From 2009 to 2017, the rate of same-day discharge increased from 4.3% to 19.5% for femoral-access PCI and from 9.9% to 39.7% for radial-access PCI. Hospital-level variation in the use of same-day discharge persisted throughout (median odds ratio adjusted for year and radial access: 4.15). Risk-adjusted 30-day mortality did not change over time, while risk-adjusted rehospitalization decreased over time and more quickly for same-day discharge (P for interaction<0.001). In the past decade, a large increase in the use of same-day discharge following elective PCI was not associated with worse 30-day mortality or rehospitalization. Hospital-level variation in same-day discharge may represent an opportunity to reduce costs without compromising patient outcomes.

Role of ADL Independence in Postacute-Care Rehabilitation Service Needs in the Elderly Abdominal Surgery Population

Abstract Date Presented Accepted for AOTA INSPIRE 2021 but unable to be presented due to online event limitations. More than half of all surgical patients are age 65 and older, and research suggests that a majority of these patients will require postacute-care (PAC) rehabilitation services. Despite the growing costs, characteristics related to requiring PAC in the elderly abdominal surgery population are not well studied. This project aims to describe discharge trends, as well as factors related to requiring placement at a skilled-nursing facility in the elderly abdominal surgery population. Primary Author and Speaker: Erika Dobson Contributing Authors: Rebecca Julian, Hailey Zanette

Trend analyses for discharge-recharge of Tacin karstic spring (Kayseri, Turkey)

Vast research is conducted around the world in order to determine the effects of climate change on water resources. Determining and preserving the rechanging characteristics of karstic springs has an important place in water resources management studies. In the present study, the variation trends of climate parameters, affecting the discharge trend of the Tacin karstic spring in Kayseri, Turkey and the spring discharge, were analyzed. For this purpose, the monthly mean discharge flow of the karstic spring between the years 1975 and 2017 and the monthly average temperatures and precipitation parameters belonging to the meteorological stations close to the spring (Kayseri, Pınarbaşı, Gemerek and Şarkışla) were adopted. In the trend analyses, the non-parametric Spearman Rho (SR), Mann Kendall (MK) and Şen-Innovative Trend analysis tests (Şen-ITA) were used in addition to the non-linear tests. Accordingly, a reduction was observed in the change trend of the precipitation parameter of Pınarbaşı and Kayseri stations and an increase in the respective measure of the Gemerek and Şarkışla stations while a noticeable decrease took place in the flow discharge of the Tacin karstic spring. The temperature parameter underwent a similar increase in all of the four stations meanwhile. Consequently, the decrease trend in the flow discharges of the Tacin karstic aquifer was inferred to stem from the reduction in the precipitation trend, observed in the southern part of the karstic aquifer.

INVESTIGATING THE RELATIONSHIP BETWEEN CHANGES IN ATMOSPHERIC GREENHOUSE GASES AND DISCHARGE FLUCTUATIONS IN THE BASIN OF ARAS RIVER

In this study, the relationship between changes in atmospheric greenhouse gases and discharge fluctuations was investigated in the basin of Aras river. To this end, we used two sets of data including greenhouse gases (carbon dioxide, methane and nitrogen oxide) and discharge data in the Aras river basin during a period of 41 years (1968-2009). Furthermore, Pearson correlation, linear and polynomial regression, standard Z scores and Mann-Kendall test were employed. The results of investigating the discharge changes in the basin indicate its monthly and annual decreasing trend. Also, the results of Pearson correlation revealed that the decreasing trend of discharge in the basin has a close relationship with the trend of changes in carbon dioxide and methane. At a confidence level of 99%, except in summer months, almost for all months, there was a negative correlation with discharge of the basin that refers to the decline of discharge in the basin along with the increase of these gases in the environment. The greatest effect of greenhouse gases was observed in the months of December, January, February, March, and April. Mann-Kendall indicated the significance of the change trend in the discharge of the basin. On a monthly or annual basis in all months of the year, this change trend is quite significant.

Same-day discharge across FPMRS surgical cases is safe and feasible: A 10-year single-surgeon experience.

Enhanced recovery after surgery protocols and increased attention to value-based care have led to the reconsideration of routine postoperative admission in female pelvic medicine and reconstructive surgery (FPMRS) cases. We aimed to assess trends in same-day discharge (SDD) and associated readmissions and emergency room visits in a single-surgeon 10-year experience. The electronic medical record was queried for 30-day outcomes (readmission and emergency department visits with associated indications) for all cases performed between June 2010 and August 2020 by a single FPMRS surgeon. Non-FPMRS specialty cases were excluded. Patient characteristics and 30-day outcomes were compared based on SDD status for the overall cohort as well as the subset of cases traditionally involving an overnight stay (i.e., robotic transabdominal, apical prolapse repair). 1793 surgeries were identified and analyzed, including 357 apical prolapse repairs, 370 slings, 392 neuromodulation and 114 complex mesh excisions. The majority (79.1%) had SDD. For admitted patients, mean length of stay was 1.5 (1.3) days. Among cases traditionally involving overnight stay, rates of SDD were significantly higher in 2020 than 2010 (84% vs. 32%, p < 0.001), and increased over time. Overall rates of 30-day readmission and ED visits were low (1.9% and 2.6%, respectively) and did not differ based on SDD status (p = 0.76). Readmissions occurred at mean 11.6 (7.0) days, most commonly for urinary tract infection (13/34). SDD is not associated with increased 30-day readmission or ED visits across a wide breadth of FPMRS cases. SDD is safe and feasible in the majority of FPMRS cases.

Tumor-Related and Patient-Related Variables Affecting Length of Hospital Stay Following Vestibular Schwannoma Microsurgery.

Review a single institution's vestibular schwannoma (VS) microsurgery experience to determine (1) correlations between demographics, comorbidities, and/or surgical approach on hospital length of stay (LOS) and discharge disposition and (2) trends in surgical approach over time. Retrospective case series from a multidisciplinary skull base program at a tertiary care, academic hospital. All adult (>18 years) patients undergoing primary microsurgery for VS between 2008 and 2018 were included. A total of 147 subjects were identified. Surgical approach was split between middle fossa (MF) (16%), retrosigmoid (RS) (35%), and translabyrinthine (TL) (49%) craniotomies. For the 8% of patients had other than routine (OTR) discharge. Mean LOS was significantly longer for patients undergoing RS than either MF or TL. Brainstem compression by the tumor was associated with longer LOS as were diagnoses of chronic obstructive pulmonary disease (COPD) and peripheral vascular disease (PVD). For all discharges, the 40 to 50- and 50 to 60-year-old subgroups had significantly shorter LOS than the 70-years-and-older patients. For the 92% of patients routinely discharged, there was a significantly shorter LOS in the 40 to 50-year-olds compared to the 70-years-and-older patients. There was a significant shift in surgical approach from RS to TL over the study period. Over 90% of VS microsurgery patients were routinely discharged with a median hospital LOS of 3.2 days, both of which are consistent with published data. There is an inverse relationship between age and LOS with patients older than 70 years having significantly longer LOS. Brainstem compression, COPD, PVD, and the RS approach negatively affect LOS. 4.

Trends in Early Discharge and Associated Costs after Transcatheter Aortic Valve Replacement: A National Perspective

Objective The current study aims to report trends of early discharges and identify associated direct costs using a nationally representative database of real-world data experience. Methods We used nationally weighted data on all patients who had transfemoral transcatheter aortic valve replacement (TAVR) from 2012 to 2017 and discharged alive from the National Inpatient Sample. Patients were divided into early (discharge ≤3 days of admission) and late discharge. Demographics and clinical characteristics were compared. Trends in early discharge and costs associated with admissions were analyzed over the study period. Results Of the 125,188 patients identified, 59,424 (46.9%) were discharged early. The proportion of early discharge increased from 15% in early 2012 to 68% in late 2017 ( P &lt; 0.001), with the largest increase occurring from 2014 to 2015. Overall, the average cost of TAVR decreased from $58,408 in 2012 to $49,875 in 2017 ( P &lt; 0.001). Compared to late discharge, patients discharged early reported costs savings of ≥$20,000 over the study period. Among the early discharge group, no significant differences in costs were observed for patients discharged on 0 to 1, 2, or 3 days after the procedure. Conclusions Postoperative length of stay after TAVR has decreased dramatically within the last decade with an observed reduction in procedural costs. While discharge within 3 days appeared cost effective, no differences in costs were noted among patients discharged ≤3 days.

Time trends in hospital discharges in patients aged 85\u2009years and older in Spain: data from the Spanish National Discharge Database (2000\u20132015)

BackgroundThe aging population is an increasing concern in Western hospital systems. The aim of this study was to describe the main characteristics and hospitalization patterns in inpatients aged 85 years or more in Spain from 2000 to 2015.MethodsRetrospective observational study analyzing data from the minimum basic data set, an administrative registry recording each hospital discharge in Spain since 1997. We collected administrative, economic and clinical data for all discharges between 2000 and 2015 in patients aged 85 years and older, reporting results in three age groups and four time periods to assess differences and compare trends.ResultsThere were 4,387,326 discharges in very elderly patients in Spain from 2000 to 2015, representing 5.32% of total discharges in 2000–2003 and 10.42% in 2012–2015. The pace of growth was faster in older age groups, with an annual percentage increase of 6% in patients aged 85–89 years, 7.79% in those aged 90–94 years, and 8.06% in those aged 95 and older. The proportion of men also rose (37.30 to 39.70%, p < 0.001).The proportion of patients that died during hospital admission decreased from 14.64% in 2000–2003 to 13.83% in 2012–2015 (p < 0.001), and mean length of stay from 9.98 days in 2000–2003 to 8.34 days in 2012–2015.Some of the most frequent primary diagnoses became even more frequent relative to the total number of primary diagnoses, such as heart failure (7.84 to 10.62%), pneumonia (6.36 to 7.36%), other respiratory diseases (3.87 to 8.49%) or other alterations of urinary tract (3.08 to 5.20%). However, there was a relative decrease in the proportion of femoral neck fractures (8.07 to 6.77%), neoplasms (7.65 to 7.34%), ischemic encephalopathy (6.97 to 5.85%), COPD (4.23 to 3.15%), ischemic cardiomyopathy (4.20 to 8.49%) and cholelithiasis (3.07 to 3.28%).ConclusionsDischarges in the very elderly population are increasing in both relative and absolute terms in Spanish hospitals. Within this group, discharged patients are getting older and more frequently male. The mean length of stay and the proportion of patients that died during hospital admission are decreasing. Acute-on-chronic organ diseases, neoplasms, acute cardiovascular diseases, and infections are the most common causes of discharge.

Study on vehicle drag reduction simulation based on Suzen–Huang model

In the past numerical simulation of plasma and fluid coupling, the usually used Suzen numerical simulation model has the defect that the error increases with the increase in excitation voltage. The static test of the ionic wind is used to modify the parameters of the Suzen simulation model, and it applied the modified Suzen model to the flow control of the automobile external flow field, which shows good consistency with the wind tunnel test results. Results show that the Suzen model modified by the static test results of the ionic wind is suitable for different excitation voltage conditions. The corrected body force and charge density distribution conform to the change trend of plasma discharge, and the error between the maximum ionic wind velocity obtained by simulation and the test result is within 4%; the modified Suzen model is successfully applied to the plasma flow control of automobile aerodynamic drag reduction. The results show that the exciter suppresses the generation of periodic separation vortices in the tail of the model, which makes the vorticity in the wake significantly decrease, thereby reducing the energy dissipation and the aerodynamic drag of the model. Through the research in this paper, the modified Suzen model reduces the simulation error. Plasma flow control technology is applied to the field of automobile aerodynamic drag reduction, which has accumulated important experience methods and data foundation for the engineering application of this technology. It also provides new methods for improving vehicle aerodynamic performance and fuel economy.

Multi-variate infilling of missing daily discharge data on the Niger basin

Abstract The Niger basin has experienced historical drought episodes and floods in recent times. Reliable hydrological modelling has been hampered by missing values in daily river discharge data. We assessed the potential of using the Multivariate Imputation by Chained Equations (MICE) to estimate both continuous and discontinuous daily missing data across different spatial scales in the Niger basin. The study was conducted on 22 discharge stations that have missing data ranging from 2% to 70%. Four efficiency metrics were used to determine the effectiveness of MICE. The flow duration curves (FDC) of observed and filled data were compared to determine how MICE captured the discharge patterns. Mann-Kendall, Modified Mann-Kendall, Pettit and Sen's Slope were used to assess the complete discharge trends using the gap-filled data. Results shows that MICE near perfectly filled the missing discharge data with Nash-Sutcliffe Efficiency (NSE) range of 0.94–0.99 for the calibration (1992–1994) period. Good fits were obtained between FDC of observed and gap-filled data in all considered stations. All the catchments showed significantly increasing discharge trend since 1990s after gap filling. Consequently, the use of MICE in handling missing data challenges across spatial scales in the Niger basin was proposed.

Changing freshwater contributions to the Arctic

The pan-Arctic domain is undergoing some of Earth’s most rapid and significant changes resulting from anthropogenic and climate-induced alteration of freshwater distribution. Changes in terrestrial freshwater discharge entering the Arctic Basin from pan-Arctic watersheds significantly impact oceanic circulation and sea ice dynamics. Historical streamflow records in high-latitude basins are often discontinuous (seasonal or with large temporal gaps) or sparse (poor spatial coverage), however, making trends from observed records difficult to quantify. Our objectives were to generate a more continuous 90-year record (1981–2070) of spatially distributed freshwater flux for the Arctic Basin (all Arctic draining rivers, including the Yukon), suitable for forcing ocean models, and to analyze the changing simulated trends in freshwater discharge across the domain. We established these data as valid during the historical period (1971–2015) and then used projected futures (preserving uncertainty by running a coupled climate-hydrologic ensemble) to analyze long-term (2021–2070) trends for major Arctic draining rivers. When compared to historic trends reported in the literature, we find that trends are projected to nearly double by 2070, with river discharge to the Arctic Basin increasing by 22% (on average) by 2070. We also find a significant trend toward earlier onset of spring freshet and a general flattening of the average annual hydrograph, with a trend toward decreasing seasonality of Arctic freshwater discharge with climate change and regulation combined. The coupled climate-hydrologic ensemble was then used to force an ocean circulation model to simulate freshwater content and thermohaline circulation. This research provides the marine research community with a daily time series of historic and projected freshwater discharge suitable for forcing sea ice and ocean models. Although important, this work is only a first step in mapping the impacts of climate change on the pan-Arctic region.

Climate signals in river flood damages emerge under sound regional disaggregation

Climate change affects precipitation patterns. Here, we investigate whether its signals are already detectable in reported river flood damages. We develop an empirical model to reconstruct observed damages and quantify the contributions of climate and socio-economic drivers to observed trends. We show that, on the level of nine world regions, trends in damages are dominated by increasing exposure and modulated by changes in vulnerability, while climate-induced trends are comparably small and mostly statistically insignificant, with the exception of South & Sub-Saharan Africa and Eastern Asia. However, when disaggregating the world regions into subregions based on river-basins with homogenous historical discharge trends, climate contributions to damages become statistically significant globally, in Asia and Latin America. In most regions, we find monotonous climate-induced damage trends but more years of observations would be needed to distinguish between the impacts of anthropogenic climate forcing and multidecadal oscillations.

Glacio-Nival Regime Creates Complex Relationships between Discharge and Climatic Trends of Zackenberg River, Greenland (1996–2019)

Arctic environments experience rapid climatic changes as air temperatures are rising and precipitation is increasing. Rivers are key elements in these regions since they drain vast land areas and thereby reflect various climatic signals. Zackenberg River in northeast Greenland provides a unique opportunity to study climatic influences on discharge, as the river is not connected to the Greenland ice sheet. The study aims to explain discharge patterns between 1996 and 2019 and analyse the discharge for correlations to variations in air temperature and both solid and liquid precipitation. The results reveal no trend in the annual discharge. A lengthening of the discharge period is characterised by a later freeze-up and extreme discharge peaks are observed almost yearly between 2005 and 2017. A positive correlation exists between the length of the discharge period and the Thawing Degree Days (r=0.52,p&lt;0.01), and between the total annual discharge and the annual maximum snow depth (r=0.48,p=0.02). Thereby, snowmelt provides the main source of discharge in the first part of the runoff season. However, the influence of precipitation on discharge could not be fully identified, because of uncertainties in the data and possible delays in the hydrological system. This calls for further studies on the relationship between discharge and precipitation. The discharge patterns are also influenced by meltwater from the A.P. Olsen ice cap and an adjacent glacier-dammed lake which releases outburst floods. Hence, this mixed hydrological regime causes different relationships between the discharge and climatic trends when compared to most Arctic rivers.

Effect of Rainfall Variability on Spring Discharge in the Masingini Catchment, Zanzibar-Tanzania

Spring discharge from the Masingini catchment plays a crucial role in the Zanzibar Municipality water supply scheme. However, there has been remarkable attenuation in spring discharge over the years due to a change in rainfall patterns. The study's objective was to assess the effect of rainfall variability on Mtoni and Bububu springs discharge in the Masingini catchment. It analyzed rainfall variability on the Masingini catchment between 1992 and 2018 to assess spring discharge at least ten years before and after the water policy. The monthly rainfall data was collected from Tanzania Meteorological Agency in the Zanzibar office. The spring discharge data was collected from Zanzibar Water Authority and supplemented by field measurements of monthly groundwater levels for wet and dry seasons from fifteen boreholes. The data analysis was carried out using the M-K test. The results revealed a non-significant downward trend in seasonal rainfall over rainfall stations due to the decline of seasonal rainfall over the years. Annual rainfall showed a significant decreasing trend for Kizimbani Agromet station (p &amp;lt; 0.05). On the other hand, the groundwater level dropped by an average of 5±2.6m between the long rainy and dry seasons. The maximum and minimum spring discharges coincide with wet and dry seasons, respectively. There was a significant decreasing trend in annual spring discharge at α = 0.05 and α = 0.01 for Mtoni and Bububu spring discharge, respectively. The M-K revealed a significantly positive correlation of annual spring discharge and rainfall, τ = 0.333 and τ = 0.453 for Mtoni and Bububu spring, respectively, implying that discharge increases as rainfall increases. The average daily discharge of Mtoni and Bububu spring declined by 23.9% and 18.9%, respectively, before and after water policy. The study concluded that rainfall variability was the primary hydroclimate factor for declining spring discharge on the catchment.