Recession Analysis Research Articles

Soil frost effects on streamflow recessions in a subarctic catchment

AbstractThe Arctic is warming rapidly. Changing seasonal freezing and thawing cycles of the soil are expected to affect river run‐off substantially, but how soil frost influences river run‐off at catchment scales is still largely unknown. We hypothesize that soil frost alters flow paths and therefore affects storage–discharge relations in subarctic catchments. To test this hypothesis, we used an approach that combines meteorological records and recession analysis. We studied streamflow data (1986–2015) of Abiskojokka, a river that drains a mountainous catchment (560 km2) in the north of Sweden (68° latitude). Recessions were separated into frost periods (spring) and no‐frost periods (summer) and then compared. We observed a significant difference between recessions of the two periods: During spring, discharge was linearly related to storage, whereas storage–discharge relationships in summer were less linear. An analysis of explanatory factors showed that after winters with cold soil temperatures and low snowpack, storage–discharge relations approached linearity. On the other hand, relatively warm winter soil conditions resulted in storage–discharge relationships that were less linear. Even in summer, relatively cold antecedent winter soils and low snowpack levels had a propagating effect on streamflow. This could be an indication that soil frost controls recharge of deep groundwater flow paths, which affects storage–discharge relationships in summer. We interpret these findings as evidence for soil frost to have an important control over river run‐off dynamics. To our knowledge, this is the first study showing significant catchment‐integrated effects of soil frost on this spatiotemporal scale.

Hydrologic functioning of the deep critical zone and contributions to streamflow in a high‐elevation catchment: Testing of multiple conceptual models

AbstractHigh‐elevation mountain catchments are often subject to large climatic and topographic gradients. Therefore, high‐density hydrogeochemical observations are needed to understand water sources to streamflow and the temporal and spatial behaviour of flow paths. These sources and flow paths vary seasonally, which dictates short‐term storage and the flux of water in the critical zone (CZ) and affect long‐term CZ evolution. This study utilizes multiyear observations of chemical compositions and water residence times from the Santa Catalina Mountains Critical Zone Observatory, Tucson, Arizona to develop and evaluate competing conceptual models of seasonal streamflow generation. These models were tested using endmember mixing analysis, baseflow recession analysis, and tritium model “ages” of various catchment water sources. A conceptual model involving four endmembers (precipitation, soil water, shallow, and deep groundwater) provided the best match to observations. On average, precipitation contributes 39–69% (55 ± 16%), soil water contributes 25–56% (41 ± 16%), shallow groundwater contributes 1–5% (3 ± 2%), and deep groundwater contributes ~0–3% (1 ± 1%) towards annual streamflow. The mixing space comprised two principal planes formed by (a) precipitation‐soil water‐deep groundwater (dry and summer monsoon season samples) and (b) precipitation‐soil water‐shallow groundwater (winter season samples). Groundwater contribution was most important during the wet winter season. During periods of high dynamic groundwater storage and increased hydrologic connectivity (i.e., spring snowmelt), stream water was more geochemically heterogeneous, that is, geochemical heterogeneity of stream water is storage‐dependent. Endmember mixing analysis and 3H model age results indicate that only 1.4 ± 0.3% of the long‐term annual precipitation becomes deep CZ groundwater flux that influences long‐term deep CZ development through both intercatchment and intracatchment deep groundwater flows.

The role of landscape properties, storage and evapotranspiration on variability in streamflow recessions in a boreal catchment

Streamflow recession analysis provides valuable insights into catchment functioning that can be related to runoff generation, storage retention and baseflow dynamics. As an integrated characteristic, recession analysis is particularly useful in catchment comparison studies to help explain drivers of spatial and temporal variability in hydrological behavior. Here, five years of hourly streamflow data from 14, partly nested, catchments within a 68 km2 boreal forest landscape in Northern Sweden were used to explore spatiotemporal variation in hydrological processes through recession analysis. The aim of this study was to better understand spatial variation in runoff generation and storage-discharge dynamics across the landscape, as well as the relation to landscape properties. Due to high collinearity between variables, partial least square regression was used to quantify the associations between recession characteristics and catchment properties, as well as to identify key variables controlling recession behavior. We analyzed recession characteristics using both an aggregated approach including all recession data and individual recession events. The analyses based on individual recession events, indicated that catchment topography, quantified by indices such as mean slope or elevation above the stream network, is a primary control on the recession behavior during relatively high flows, whereas catchment area gains importance when flows are relatively low. The proportion of sediment and deep soils also controlled recession behavior. Furthermore, we found that recession characteristics are influenced by both evapotranspiration (ET) and proxies of antecedent catchment storage, but that the patterns were different depending on catchment properties. ET was less influential in catchments with deeper soils and larger catchment area. Shifts in recession rates were primarily related to variation in storage, with faster streamflow recessions occurring during periods with low storage. The results demonstrate the influence of catchment properties on recession behavior, and we found great value in analyzing individual recession events for an increased understanding of spatial and temporal recession characteristics. When recession properties were lumped together, the relationships to catchment characteristics were obscured. This indicates the value of more detailed analyses, at least under the strongly seasonal hydroclimatic conditions of this site.

Assessing the Catchment Storage Function Through a Dual‐Storage Concept

AbstractCatchment storage controls most ecohydrological processes by modulating, among other things, the hydrological connectivity between landscape units. However, little is known about the internal dynamics of storage and its feedback with hydraulic connectivity. Here we evaluate the capability of a combined lumped approach (i.e., combining catchment water balance and recession analysis) to partition total dynamic storage (from the water balance) into hydraulically connected (the part feeding stream estimated from recession analysis) and hydraulically disconnected components (i.e., the remaining storage driven by precipitation and evapotranspiration). Results from our combined approach were compared to a point measurement‐based estimation (using wells and soil moisture data) from the experimental Weierbach catchment in Luxembourg (0.45 km2). We found good agreement for the hydraulically connected storage but contrasted results for the hydraulically disconnected storage. During wet periods, the latter were characterized by opposite dynamics and our lumped approach showed step‐by‐step deviations. Overall, these results indicated a good capability of our approach to partition storage, as well as its sensitivity to systematic and random deviations. Considering these possible deviations, this new conceptualization of storage provides relevant and quantifiable information about catchment state (i.e., storage dominated or release dominated). This is further highlighted when represented in a dual‐storage plot (hydraulically disconnected vs. connected storage). Compared to classic storage‐discharge relationships, it allows catchment efficiency (capacity of the catchment to convert storage into streamflow) to be assessed without the need for additional data. We expect that this mechanistic conceptualization of the storage function will provide new opportunities for assessing catchment functioning and catchment classification.

An Analysis of Nigerian Recession

Over the years, Nigeria depends on crude oil proceeds as the major source of national income, foreign exchange and external reserves. This dependence coupled with the huge cost of running and maintaining the political structure among other factors prove disastrous by leading the economy to the worst recession in decades. We therefore, chronicle the origin, effects and way out of the recession via trend analysis and desk review. Having analyzed the remote and immediate causes of the recession, we observed that the dependence on crude oil whose price is highly volatile made the Nigerian economy susceptible to shocks. Hence the oil price and output shocks coupled with high cost of governance, excessive importation, corruption, sudden implementation of Treasury Single Account (TSA), insurgency and Niger Delta Militancy among other factors destabilized all macroeconomic variables and threw the economy to the worst scenario of recession (stagflation). Thus, diversification of the Nigerian economy by prioritizing agriculture and manufacturing, massive fiscal stimulus plan to enhance domestic infrastructure and production, re-injection of recovered loots, resolution of Niger Delta militancy among other policies are recommended to ameliorate the effects of current recession and strengthen the structures of the economy in order to prevent reoccurrence of economic recession in the country.

Baseflow estimation for catchments in the Loess Plateau, China

Baseflow is the portion of streamflow that originates from groundwater. It is pivotal to groundwater supply as well as the interactions between groundwater and surface water. In the Loess Plateau of China, the baseflow plays a fundamental role in sustaining the aquatic ecosystem. Rational estimation of baseflow is of critical importance for understanding the functioning of the groundwater system and informing management of regional water resources. In this study, a two-well parameterised digital filter was used to separate baseflow from observed daily total streamflow on the Weihe River Basin. Two parameters (maximum baseflow index (BFImax) and the recession constant) of this filter were estimated using UKIH and a recession analysis with physical meaning, respectively. The results show that the baseflow index increased from the upstream to downstream (0.27–0.32) of the Weihe River, and the baseflow of the river is summer dominant. In general, the baseflow has been increasing gradually owing to the implementation of soil conservation measures. This study provides an understanding of baseflow response to seasonal variability and water environmental management in basin scale.

Hydrogeological Parameter Determination in the Southern Catchments of Taiwan by Flow Recession Method

The understanding of hydrogeological characteristics and groundwater flow processes in aquifers is crucial for the determination of sustainable groundwater resource development as well as hydrological management and planning. In the past, information on hydrogeological characteristics was mainly acquired through point field measurement such as borehole geophysical techniques and field aquifer hydraulic testing. However, in view of the cost limitations and scale applicability of these methods, low-flow recession analysis techniques that utilize streamflow data can be used as alternative low-cost methods to reversely back-calculate hydrogeological parameters based on the hydrological processes by which groundwater from aquifers is naturally discharged to rivers. We chose Southern Taiwan as the study area for the estimation of the recession index (K), which is representative of catchment discharge behavior during both the dry and wet seasons, to determine seasonal differences in the aquifer flow regime and to estimate the following three hydrogeological parameters: hydraulic conductivity (k), specific yield (Sy), and transmissivity (T). Based on the field test reports of the locations of groundwater observational wells on the Chianan and Pingtung plains, the study area was divided into the Chianan sub-area (Zengwun, Yanshui, and Erren river basins) and the Kaoping sub-area (Kaoping, Donggang, and Linbian river basins). The estimation results of the present study were compared to the field test results. The results showed significant differences in the recession index K between the dry and wet seasons. Slight differences between the estimated hydrogeological parameters and the field test results were also observed for the two sub-areas because of differences in scale. Furthermore, regional differences in the estimation results were found to be consistent with the distribution of geological structures, which indicates a high degree of feasibility in the application of flow recession methods for catchment-scale hydrogeological parameter determination.

Confirmation of a Short‐Time Expression for the Hydrograph Rising Limb of an Initially Dry Aquifer Using Laboratory Hillslope Outflow Experiments

AbstractThe objective of this study is to assess the validity of a theoretical expression for the outflow from an initially dry aquifer subject to recharge. This equation states that, for small values of time, this outflow is proportional to the square root of time. Here we report on experiments performed with two laboratory hillslopes in the Wageningen rainfall simulator. Three different aquifer slopes were investigated with four replicates for each slope. The relations between the measured outflows and the square root of time exhibited very high coefficients of determination (all but one >0.9). The aquifer saturated hydraulic conductivity (k) and drainable porosity were determined using a base flow recession analysis, with k being consistent with soil physical laboratory measurements. The recharge rates obtained using the coefficient of the short‐time expression and the steady state discharge were consistent as well. Overall, these results confirm the theoretical relationship between the aquifer outflow for the hydrograph rising limb and the square root of time.

Spatio‐temporal variability in contributions to low flows in the high Alpine Poschiavino catchment

AbstractIn order to predict streamflow accurately during extended dry periods, we need to understand the spatial variability of low flows and the extent to which it is affected by the spatial organization and drainage of catchment subsurface storage areas. This is especially true in Alpine catchments with widely varying topography, lithology, sediment deposits, and soil properties. Field measurements in the Poschiavino catchment in southern Switzerland, during a winter recession period without recharge, provided a unique opportunity to demonstrate the connections between subsurface storage areas, low flows, and their variability. We measured discharge in four nested sub‐catchments during seven field campaigns in the winter of 2013–2014. We analysed stream water electrical conductivity (EC) and water chemistry to identify the areas contributing to low‐flow discharge and estimated their contributions. Sediment cover type and thickness were mapped using a recently developed tool for geomorphology‐based storage classification of mountainous terrain, to determine the physical properties of the subsurface storage areas contributing to low‐flow discharge. Recession analyses combined with water chemistry data allowed the detection of different drainage timescales and the estimation of storage potential of the unconsolidated (Quaternary) deposits. We found substantial spatial variation in storage depletion between the sub‐catchments, ranging from 54 mm to 200 mm for the four‐month monitoring period. Variability in low‐flow contributions from different catchments and different recession behavior could be related to the differences in the estimated storage potential. For some point sources, we could quantify the contributing area and thus quantify low flows at the hillslope scale. Overall, the low‐flow variability is mostly related to the fraction of precipitation that recharges subsurface storage areas and to the properties influencing their drainage. To capture these processes, we suggest low‐flow geomorphological mapping approaches that consider not only morphometric (shape of the landscape) and geologic (properties of the bedrock) controls but also the water storage potential of debris cover and weathered rock.

Groundwater recharge assessment in a rural, arid, mid-mountain basin in North-Central Chile

ABSTRACTA basic component of any hydrogeological study is the magnitude and temporal variation of groundwater recharge. This can be difficult to assess accurately, particularly in arid and semi-arid rainfed mid-mountain zones, as is the situation in the rural, low population density zones of North-Central Chile. In this study, recharge in the Punitaqui Basin, North-Central Chile, was characterized, contrasting the results of two methods: a modified Thornthwaite-Mather (MTM) and discharge recession analysis (DRA). We found a recharge rate of between 1 and 4% of average annual precipitation. Average recharge estimated by the MTM method is consistently higher than that estimated by DRA. Also, DRA tends to smooth the recharge values, resulting in a lower inter-annual variation coefficient. Both methods identified a threshold value of total annual precipitation, above which recharge can be expected to occur, of the order of 180 mm year−1, consistent with values reported in similar areas.

Real sectoral spillovers: A dynamic factor analysis of the great recession

Dynamic factor methods are used to identify the impact of common and idiosyncratic shocks on sixteen U.S. nonfarm business sectors. This paper then studies changes in the transmission of these shocks across sectors during the Great Recession, and evaluates the cross-sectoral spillovers. The Great Recession is found to be largely a time of heightened impact of common shocks–which accounts for 3/4 of aggregate volatility–and large spillovers of negative finance-related shocks. In addition, prior to the Recession, aggregate fluctuations are mainly driven by sector-specific shocks, in contrast with findings from previous studies.

Groundwater-flow characterization in a multilayered karst aquifer on the edge of a sedimentary basin in western France

On the edge of sedimentary basins, burial of geological layers can involve the formation of confined karst aquifers. In some cases, relationships between confined and unconfined karst aquifers can exist and imply an increased difficulty in delineating contributive areas of karst system outlets with accuracy. This work aims to develop a multi-disciplinary approach to highlight groundwater exchanges between multilayered karst aquifers feeding a single spring.Toulon Springs, located in western France, provides the opportunity to study relationships between two multilayered karst aquifers. Hydrograph and chemograph analysis coupled with principal component analysis (PCA) are used to evaluate groundwater-flow origins on the northern edge of a sedimentary basin. Natural hydrodynamic responses (baseflow recession analysis, auto-cross correlation function) show an important volume of water located in a saturated zone of the Toulon karst system. Significant contrasts in water quality as a function of the hydrological regime (flood, recession, and baseflow regime) and comparison with shallow and deep water show the participation of a deep aquifer supporting the flow of Toulon Springs.

Applicability Assessment of Estimation Methods for Baseflow Recession Constants in Small Forest Catchments

In South Korea, since small forest catchments are located upstream of most river basins, the baseflow from these catchments is important for a clean water supply to downstream areas. Baseflow recession analysis is widely recognized as a valuable tool for estimating the baseflow component of the stream hydrograph. However, few studies have applied this tool to small forest catchments. So, this study was conducted to assess the applicability of the recession analysis methods proposed in previous studies. The data used were long-term rainfall-runoff data from 1982 to 2011 in the Gwangneung coniferous (GC) and deciduous (GD) forest catchment in Gyeonggi-do, South Korea. For the applicability assessment, six recession constant estimation methods, which were used by previous studies, were selected. The recession constants of the GC and GD catchments were calculated, and applicability assessments were conducted by comparing the recession predictions and baseflow separations. As a result, the recession constants for GC and GD were 0.8480 and 0.9235, respectively. This clear difference may be due to the different forest cover in each area. The correlation regression line, AR(1) model, and the Vogel and Kroll method showed lower error rates and appropriate baseflow indexes compared with other methods.

Quantitative analysis of surface recession on carbon-based ablators using a high-resolution non-contact profilometer

This paper proposes a systematic procedure for the quantitative analysis of the surface changes caused by ablation of carbon-based ablators using a high-resolution non-contact profilometer. The ablation tests were performed under high enthalpy flow conditions using a 0.4MW arc-heated wind tunnel. The high-resolution profilometer was used to measure the surface data of carbon-based ablators. The key parameters for the analysis of the surface changes, such as surface recession and roughness, were calculated by the proposed procedure. In addition, a finite element model of the sample after the ablation test was constructed from the measured surface data. The proposed procedure can be effectively used to perform various analyses of the ablated surface using the measured data and numerical analysis method.

The Relevance of Root's Convergence with Trauma from Occlusion.

Background:The relevance of root's convergence with trauma from occlusion has not been widely studied. Anatomically, alveolar bone support can be divided into several levels. The root which is convergent gives a critical mass of alveolar bone support to the teeth so that it is inadequate to stabilize the tooth.Aims:The purpose of the study is to observe the relevance of root's convergence with traumatic from occlusion.Settings and Design:This was an observational retrospective design.Subjects and Methods:Samples in this study consist of periapical radiograph of the maxillary and mandibular first molar teeth from the patients with periodontitis, which are aggravated with trauma from occlusion. For the root's convergence measurement, we use a line on the outer edge of the mesial, distal, occlusal, and apical planes of the tooth. To get the cutoff point of the root convergence value, receiver operating characteristic-curve test is performed.Statistical Analysis Used:Spearman test results, based on the analysis of gingival recession and loss of attachment, indicating that each increase of root convergence value will be followed by a decrease of attachment.Conclusions:Tooth which has a convergent/very convergent root contour can contribute to trauma from occlusion.

Analysis of Mt Kenya Glaciers Recession Using GIS and Remote Sensing

This research analyses the changes in coverage Mt Kenya glaciers in a bid find what has been causing the retreat of these glaciers. Optical Landsat data for 1984 to 2017 and Climatic data of the same years were used. Glaciers and forest coverage were extracted from Landsat images and its thermal band was used to extract temperature data. Correlation with the respective year’s climatic data and forest cover area were done to justify the assumption that the shrinkage in the glaciers coverage has been caused by changes in climate and/or deforestation. Then using the historical EC Earth model climate data predictions for 1984-2017 and historical observed data for the same years, bias correction factors were computed and used to correct the future model data for the years (2018-2045). Since the data was extracted for only four points around Mt Kenya, Interpolation was then done to obtain the Precipitation and Temperature for the mountain peak (since the glaciers are found at the peak) using the IDW technique. Prediction of glacier area coverage was then done using these interpolated climate data. In order to predict the future glacier cover, linear equations of the form y = a1x1 + a2x2 +bo of the interpolated climate data (for 2018-2045) and computed glacier areas for (1984-2017) were formed. The a1 a2 and bo in the equation are constants obtained from SPSS (a statistical software). X1 and x2 are the predicted Temperature and Precipitation respectively. Predictions were done for RCP scenarios 8.5 and 4.5. The results of prediction showed that the current trend of glacier thinning is going to continue but at a slower rate compared to the rapid melting that was observed for the period 1984-2017. However, Mt Kenya glaciers are likely to have completely disappeared by the year 2100.

Noncoercive mixed equilibrium problems under pseudomonotone perturbations and applications to nonlinear evolution equations with lack of coercivity

ABSTRACTIn this paper, we study the existence of solutions for noncoercive mixed equilibrium problems which are described by the sum of a maximal monotone bifunction and a pseudomonotone (or quasimonotone) bifunction in the sense of Brézis. Our approach is based on recession analysis and on recent results established by the authors for the existence of solutions of mixed equilibrium problems under pseudomonotone perturbations. As an application, we study the existence of solutions for nonlinear evolution equations associated with a noncoercive time-dependent pseudomonotone (or quasimonotone) operator.

Modelling Coastal Cliff Recession Based on the GIM–DDD Method

The unpredictable and instantaneous collapse behaviour of coastal rocky cliffs may cause damage that extends significantly beyond the area of failure. Gravitational movements that occur during coastal cliff recession involve two major stages: the small deformation stage and the large displacement stage. In this paper, a method of simulating the entire progressive failure process of coastal rocky cliffs is developed based on the gravity increase method (GIM), the rock failure process analysis method and the discontinuous deformation analysis method, and it is referred to as the GIM–DDD method. The small deformation stage, which includes crack initiation, propagation and coalescence processes, and the large displacement stage, which includes block translation and rotation processes during the rocky cliff collapse, are modelled using the GIM–DDD method. In addition, acoustic emissions, stress field variations, crack propagation and failure mode characteristics are further analysed to provide insights that can be used to predict, prevent and minimize potential economic losses and casualties. The calculation and analytical results are consistent with previous studies, which indicate that the developed method provides an effective and reliable approach for performing rocky cliff stability evaluations and coastal cliff recession analyses and has considerable potential for improving the safety and protection of seaside cliff areas.

Networked Markets and Relational Contracts

Empirical studies of commercial relationships between firms reveal that (i) suppliers encounter situations in which they can gain in the short run by acting opportunistically---for example, delivering a lower quality than promised after being paid; and (ii) good conduct is sustained not exclusively by formal contracts but through informal relationships and the expectation of future business. In such relationships, the need to offer each supplier a large enough share of future business to deter cheating limits the number of supply relationships each buyer can sustain. The market thus becomes networked, with trade restricted to durable relationships. We propose and analyze a simple dynamic model to examine the structure of such overlapping relational contracts in equilibrium. Due to exogenous stochastic shocks, suppliers are not always able to make good on their promises even if they wish to, and so links are constantly dissolving and new ones are forming to take their place. This induces a Markov process on networks. We study how the stationary distribution over networks depends on the parameters---most importantly, the value of trade and the probability of shocks. When the rate at which shocks hit increases, as might happen during an economic downturn, maintaining incentive compatibility with suppliers requires promising each more future business and this necessitates maintaining fewer relationships with suppliers. This results in a destruction of social capital, and even if the rate of shocks later returns to its former level, it can take considerable time for social capital to be rebuilt because of search frictions. This creates a novel way for shocks to be persistent. It also suggests new connections between the theory of relational contracting, on the one hand, and the macroeconomic analysis of recessions, on the other.

Macro-Economic Analysis of Global Economic Recession 2007- 2009 and Policy Measures that Enabled Recovery of US Economy

The aim of this research paper is to attempt to understand the ‘Trilema’ which has confounded the economists on how to handle the three parameters like output, interest rates and currency effectively, to achieve the optimum level for a given economy, and even to drive an economy from recession to recovery. The authors used the US economic recession (2007-2009) event as a starting point and looked at policy interventions, both fiscal and monetary. They envisaged as to how the three chosen parameters played out over time, and what economic models can explain the basis of both the policy intervention and recovery. Our exploratory work is to understand the economic policy parameters that are critical to manage; yet which has been complicated by the US’s most open economy, to which the basic ISLM models could not support. The team finally found that the Mundell-Fleming model does make sense for open economy like US. The researchers analysed the data from US economy to see if the model is able to justify the data coming out from US from 2006-2016, when many policy interventions were taking place. The team focussed on the causes of this recession; because it was important to understand the variables underneath which caused the crisis in the first place. Another factor explored was the causes of the crisis, which to illustrate how money market was stretched by excess credit creation and excessive risk taking by the commercial banks in the post repeal of Glass–Steagall's Act in 1999. It also led to the phenomenal growth in the derivatives market and rapid integration of global capital markets across the world. This research paper also goes back to the fundamental question, as to if the monetary policy is more effective or fiscal policy is more effective? Or both need to be played in recovery. Was there even a role of fiscal policy and in what form was it deployed in US economic recovery? Finally the authors confirm that forex market equilibrium co-exist together with goods and money market equilibrium for open economies as that of US. It believed that currency markets are very important and important policy decisions should look at the long term impact on the currency stability; in the lens of competiveness of economy in the global market place.