Delineation of reservoirs using remote sensing and their storage estimate: an example of the Yellow River basin,China

Reservoirs are an integral component of water resources planning and management. Periodic and accurate assessment of the water storage change in reservoirs is an extraordinarily important aspect for better watershed management and water resources development. In view of the shortcomings of conventional approaches in locating reservoirs' spatial location and quantifying their storage, the remote sensing technique has several advantages, either for a single reservoir or for a group of reservoirs. The satellite‐based remote sensing data, encompassing spatial, spectral and temporal attributes, can provide high‐resolution synoptic and repetitive information with short time intervals on a large scale. Using remote sensing images in conjunction with Google Earth and field check of representative reservoirs, the spatial distribution of constructed reservoirs in the Yellow River basin was delineated, and their storage volume and the residence time of the stored water were estimated. The results showed that 2816 reservoirs were extracted from the images, accounting for 89·5% of the registered total. All large‐ and medium‐sized reservoirs were extracted while small reservoirs may not be extracted due to coarse resolution and cloud‐cover shadows. An empirical relationship between the extracted water surface area and the compiled storage capacity of representative reservoirs was developed. The water storage capacity was estimated to be 66·71 km³, about 92·7% of the total storage capacity reported by the authority. Furthermore, the basin was divided into 10 sub‐basins upon which the water's residence time was analysed. The water discharge in the basin has been greatly regulated. The residence time has surged to 3·97 years in recent years, ranking the Yellow River in the top three of the list in terms of residence time and flow regulation among large river systems in the world. It is expected that it will be further extended in future owing to decreasing water discharge and increasing reservoir storage capacity. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparative application of two mathematical models to predict sedimentation in Yermasoyia Reservoir,Cyprus

The Yermasoyia Reservoir is located northeast of the town of Limassol, Cyprus. The storage capacity of the reservoir is 13·6 × 10⁶ m³. The basin area of the Yermasoyia River, which feeds the reservoir, totals 122·5 km². This study aims to estimate the mean annual deposition amount in the reservoir, which originates from the corresponding basin. For the estimate of the mean annual sediment inflow into the reservoir, two mathematical models are used alternatively. Each model consists of three submodels: a rainfall‐runoff submodel, a soil erosion submodel and a sediment transport submodel for streams. In the first model, the potential evapotranspiration is estimated for the rainfall‐runoff submodel, and the soil erosion submodel of Schmidt and the sediment transport submodel of Yang are used. In the second model, the actual evapotranspiration is estimated for the rainfall‐runoff submodel, and the soil erosion submodel of Poesen and the sediment transport submodel of Van Rijn are used. The deposition amount in the reservoir is estimated by means of the diagram of Brune, which delivers the trap efficiency of the reservoir. Daily rainfall data from three rainfall stations, and daily values of air temperature, relative air humidity and sunlight hours from a meteorological station for four years (1986–89) were available. The computed annual runoff volumes and mean annual soil erosion rate are compared with the respective measurement data. Copyright © 2006 John Wiley & Sons, Ltd.     

Differences and cause analysis of changes in lakes of different supply types in the north‐western Tibetan Plateau

Most lakes of the Tibetan Plateau were experiencing quick expansion in recent decades; a detailed study on the changes in lakes of different supply types will help to understand the cause of the changes by analysing area change of 34 lakes and water level change of eight lakes in the north‐western Tibetan Plateau. All lakes are classified into three types: non‐glacier‐fed lakes, upstream lakes and glacier‐fed lakes. The glacier‐fed lakes are separated into glacier‐fed_P1 (quick expansion region) and glacier‐fed_P2 (slow expansion region). Combining the changes in precipitation, temperature and evaporation, less precipitation may be the main reason for lake shrinkage from 1976 to 1996 and quickly increasing precipitation led to the lakes' expansion from 1996 to 2000. However, after 2000, upstream lakes remained in a stable state with slight variation, non‐glacier‐fed lakes and glacier‐fed_P2 lakes exhibited a slightly increasing rate with high precipitation and high evaporation, and glacier‐fed_P1 lakes still expanded quickly. On the basis of the assumption of same precipitation and evaporation, glacial meltwater may make an important contribution (>52%) to the increase in water storage of Bangdag Co and Meima Co. The results suggest that glacial meltwater augments the increased rate of glacier‐fed_P2 lakes and plays a much more important role in the expansion of glacier‐fed_P1 lakes compared to other lakes.     

The oasis expansion and eco-environment change over the last 50 years in Manas River Valley, Xinjiang

As an elite region of human being’s residence and development, the oasis in arid areas fosters more than 90% of population, produces more than 95% of the industrial and agricultural value, although its acreage takes only 3%―5% of total arid areas[1,2]. In the last decades, the oasis exploitation, harnessing and pro-tecting regional eco-environment have been becomingone of key study objects in the sustainable develop-ment[3―7], as the global environment changes and re-gional environment becom…     

A new concept for estimating the influence of vegetation on throughfall kinetic energy using aerial laser scanning

Soil loss caused by erosion has enormous economic and social impacts. Splash effects of rainfall are an important driver of erosion processes; however, effects of vegetation on splash erosion are still not fully understood. Splash erosion processes under vegetation are investigated by means of throughfall kinetic energy (TKE). Previous studies on TKE utilized a heterogeneous set of plant and canopy parameters to assess vegetation's influence on erosion by rain splash but remained on individual plant- or plot-levels. In the present study we developed a method for the area-wide estimation of the influence of vegetation on TKE using remote sensing methods. In a literature review we identified key vegetation variables influencing splash erosion and developed a conceptual model to describe the interaction of vegetation and raindrops. Our model considers both amplifying and protecting effect of vegetation layers according to their height above the ground and aggregates them into a new indicator: the Vegetation Splash Factor (VSF). It is based on the proportional contribution of drips per layer, which can be calculated via the vegetation cover profile from airborne LiDAR datasets. In a case study, we calculated the VSF using a LiDAR dataset for La Campana National Park in central Chile. The studied catchment comprises a heterogeneous mosaic of vegetation layer combinations and types and is hence well suited to test the approach. We calculated a VSF map showing the relation between vegetation structure and its expected influence on TKE. Mean VSF was 1.42, indicating amplifying overall effect of vegetation on TKE that was present in 81% of the area. Values below 1 indicating a protective effect were calculated for 19% of the area. For future work, we recommend refining the weighting factor by calibration to local conditions using field-reference data and comparing the VSF with TKE field measurements. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

Spatial scaling properties of annual streamflow in the United States

Abstract

The spatial scaling properties of annual average streamflow is examined using records from 1 433 river basins across the continental United States. The log-linear relationship ln(E[Q^r _i]) = a + b_r ln(A_i) is representative throughout the United States, where E[Q^r _i] represents the expectation of the rth moment of annual streamflow at site i, and A_i represents drainage area. The scaling model parameters a_r and b_r follow nearly perfect linear relationships a_r = rα and b_r = rβ throughout the continental United States. We conclude that the probability distribution of annual streamflow follows simple scaling relationships in all regions of the United States. In temperate regions where climate is relatively homogeneous, scale alone describes most of the variability in the moments of annual streamflow. In the more climatically heterogeneous regions, such as in the Upper Colorado and Missouri river basins, scale alone is a poor predictor of the moments of annual flow.     

The use of caesium‐137 to estimate agricultural erosion on steep slopes in a tropical watershed

The estimation of erosion and sediment delivery rates in tropical mountain watersheds is difficult and most of the methods widely used for estimating soil erosion over large areas have serious limitations. The ¹³⁷Cs approach has potential for quantifying soil erosion because it can provide retrospective estimates of long‐term (since 1963) net sediment redistribution relatively quickly. Despite its great potential, ¹³⁷Cs has not yet been used in an extensive, reconnaissance level survey of erosion in complex tropical mountain environments. The objective of this study was to examine the applicability of the ¹³⁷Cs method to estimate erosion on steep tropical agricultural lands (23 to 80% slopes) in the Nizao watershed, a humid, tropical mountain area of the Dominican Republic. In this study we (i) examine the variation of ¹³⁷Cs in ten reference sites—eight coffee groves and two forested sites—and (ii) estimate erosion from 14 cultivated fields. The soil pool of ¹³⁷Cs ranged from to 150 to 192 mBq cm⁻² on reference sites with minimal erosion. Variability among reference sites was less than expected for such complex mountain terrain. The variability within coffee and forested reference (average CV=28%) sites was similar to the variability found on grassland and forested reference sites in the temperate zone. The estimated annual soil loss from 14 sampled fields ranged from 6 to 61 t ha⁻¹ year⁻¹ with an overall mean of 26 t ha⁻¹ year⁻¹. Overall, the soil erosion estimates found using the ¹³⁷Cs method were much lower than those often assumed for such steep tropical hillsides. These erosion estimates account for soil loss since 1963 only and it seems likely that soil losses may have been much higher in earlier decades immediately after initial forest clearing earlier in the 20th century. Copyright © 2000 John Wiley & Sons, Ltd.     

Exploring the effect of different time resolutions to calculate the rainfall erosivity factor R in Calabria,southern Italy

The rainfall erosivity factor R of the Universal Soil Loss Equation is a good indicator of the potential of a storm to erode soil, as it quantifies the raindrop impact effect on the soil based on storm intensity. The R‐factor is defined as the average annual value of rainfall erosion index, EI, calculated by cumulating the EI values obtained for individual storms for at least 22 years. By definition, calculation of EI is based on rainfall measurements at short time intervals over which the intensity is essentially constant, i.e. using so‐called breakpoint data. Because of the scarcity of breakpoint rainfall data, many authors have used different time resolutions (Δt = 5, 10, 15, 30, and 60 min) to deduce EI in different areas of the world. This procedure affects the real value of EI because it is strongly dependent on Δt. In this contribution, after a general overview of similar studies carried out in different countries, the relationship between EI and Δt is explored in Calabria, southern Italy. The use of 17 139 storm events collected from 65 rainfall stations allowed the calculation of EI for different time intervals ranging from 5 to 60 min. The overall results confirm that calculation of EI is dependent on time resolution and a conversion factor able to provide its value for the required Δt is necessary. Based on these results, a parametric equation that gives EI as a function of Δt is proposed, and a regional map of the scale parameter a that represents the conversion factor for converting fixed‐interval values of (EI₃₀)_Δt to values of (EI₃₀)₁₅ is provided in order to calculate R anywhere in the region using rainfall data of 60 min. Copyright © 2015 John Wiley & Sons, Ltd.     

A 13‐year record of erosion on badland sites in the Karoo,South Africa

Land degradation in South Africa has been of concern for more than 100 years with both climate change and inappropriate land management (overgrazing) being proposed as primary drivers. However, there are few quantitative studies of degradation and, in particular, few of erosion by water. Badlands, taken here to be the landform which results from extreme erosion, have been notably neglected. We report on 13 consecutive years of erosion pin measurements of badland erosion on 10 study sites in the Sneeuberg uplands of the eastern Karoo in South Africa. The study sites are on Holocene colluvium which mantles footslopes. They have been subject to overgrazing for at least 100 years, c. 1850–1950. Currently they are lightly grazed by sheep. The area receives about 500 mm rainfall per year. The sites are remote, with only informal, farmer‐operated, daily raingauges nearby. The nearest sub‐daily raingauge is c. 55 km distant. Also we report on an analysis of the erosion pin data which focuses on establishing the origins and context of the badlands, including the relationship between study sites and adjacent valley‐bottom gully systems; compare erosion rates on our study sites with rates determined by erosion pins on other badland sites; and discuss the implications of these erosion rates for landscape development and off‐site impacts. Net erosion rates on the study sites are relatively high compared with global badland rates and range from 3.1 to 8.5 mm yr^‐1 which may be extrapolated to 53 to 145 t ha yr^‐1 (using a measured bulk density of 1.7 g cm^‐3). However, comparisons with badland sites elsewhere are difficult because of different measuring methodologies, lithologies, climate and dominant processes. Erosion rates on the study sites are strongly influenced by rainfall amounts and, in particular, by daily rainfall events which exceed ~10 mm: this is the threshold intensity at which runoff has been observed to commence on badlands. Of significance, but of lesser influence, is weathering, mainly by wetting and drying: this prepares bare surfaces for erosion. However, questions remain regarding the role of site characteristics, and of processes at each site, in determining between‐site differences in erosion rate. Crude extrapolation of current rates of erosion, in conjunction with depths of incision into the badlands, suggests that badland development started around 200 years ago, probably as a response to the introduction of European‐style stock farming which resulted in overgrazing. We assume, but cannot quantify, the additional influence of periods of drought and burning in the erosional history of the area. Intermittent connection of these badlands to valley‐bottom gullies and therefore to small farm dams and ultimately to large water storage reservoirs increases their impact on local water resources. Copyright © 2015 John Wiley & Sons, Ltd.     

Partitioning of rainfall in a eucalypt forest and pine plantation in southeastern australia: III determination of the canopy storage capacity of a dry sclerophyll eucalypt forest

The canopy storage capacity of a dry sclerophyll eucalypt forest was determined. This required destructive sampling of three major species of trees and development of a water soakage method for the measurement of water holding capacity of all above ground components. The influence of antecedent weather conditions on canopy storage capacity was assessed. It was shown that the interactive effects of leaf area and water holding capacity of all tree components were such that the estimated canopy storage capacity (0-39 mm) was likely to change little except under extreme conditions of drought and rainfall. The effect of species composition on forest canopy storage capacity is also presented. The wetting processes are described and compared with those discussed in other studies. They are shown to be relevant to the estimation of canopy storage capacity in almost any forest.     

The influence of soil properties on the erodibility of Belgian loamy soils: A study based on rainfall simulation experiments

Twenty soils from the Leuven region were tested in the laboratory with a rainfall simulator. Their texture varied from loam to loamy sand. On the basis of the results obtained, they were classified as a function of the runoff and splash erodibility. For every soil, several properties were determined and tentatively used to explain the classifications based on the runoff and splash erodibility. Significant negative correlations were found between silt content, aggregate stability, C_5–10 index, water content at saturation, and cohesion on the one side and erodibility on the other; a positive correlation was found between sand content and erodibility.     

Quantifying large‐scale historical formation of accommodation in the Mississippi Delta

Large volumes of new accommodation have formed within the Mississippi Delta plain since the mid‐1950s in association with rapid conversion of coastal wetlands to open water. The three‐dimensional aspects and processes responsible for accommodation formation were quantified by comparing surface elevations, water depths, and vertical displacements of stratigraphic contacts that were correlated between short sediment cores. Integration of data from remotely sensed images, sediment cores, and water‐depth surveys at 10 geologically diverse areas in the delta plain provided a basis for estimating the total volume of accommodation formed by interior‐wetland subsidence and subsequent erosion. Results indicate that at most of the study areas subsidence was a greater contributor than erosion to the formation of accommodation associated with wetland loss. Tens of millions of cubic meters of accommodation formed rapidly at each of the large open‐water bodies that were formerly continuous interior delta‐plain marsh. Together the individual study areas account for more than 440 × 10⁶ × m³ of new accommodation that formed as holes in the Mississippi River delta‐plain fabric between 1956 and 2004. This large volume provides an estimate of the new sediment that would be needed just at the study areas to restore the delta‐plain wetlands to their pre‐1956 areal extent and elevations. Published 2010. This article is a US Government work and is in the public domain in the USA.     

Enhancing hydrologic modelling through the representation of traditional rainwater harvesting systems: A case study of water tanks in South India

Water tanks as traditional rainwater harvesting systems for agriculture are widely distributed in South India. They have a strong impact on hydrological processes, affecting streamflow in rivers as well as evapotranspiration. This study aims at an accurate representation of water harvesting systems in a hydrologic model to improve model performance and assessment of the catchment water balance. To this end, spatio-temporal variations of water bodies between the years 2016 and 2018 and the months of January and May 2017 were derived from Sentinel-2 satellite data to parameterize the water tanks (reservoir) parameters in the Soil and Water Assessment Tool (SWAT+) model of the Adyar basin, Chennai, India. Approximately 16% of the basin is covered by water tanks. The initial model performance was evaluated for two model setups, with and without water tanks. The best model run was selected with a multi-metric approach comparing observed and modelled monthly streamflow for 5000 model runs. The final model evaluation was carried out by comparing estimated water body areas by the model and remote sensing observations for January to May 2017. The results showed that representing water tanks in the hydrologic model led to an improvement in the representation of the seasonal variations of streamflow for the whole simulation period (2004–2018). The model performance was classified as good and very good for the calibration (2004–2011) and validation (2012–2018) periods as NSE varies between 0.67 and 0.85, KGE varies between 0.65 and 0.72, PBIAS varies between −24.1 and −23.6, and RSR varies between 0.57 and 0.39. The best fit was shown for the high and middle flow segments of the hydrograph where the coefficient of determination (R²) ranges from 0.81 to 0.97 and 0.75 to 0.81, respectively. The monthly variation of water body areas in 2017 estimated by the hydrologic model was consistent with changes observed in remote sensing surveys. In summary, the water tank parametrization using remote sensing techniques enhanced the hydrologic model's efficiency and applicability for future studies.     

水库水体近红外反射峰与叶绿素含量之间的关系初探

2007年8月至2008年9月,对厦门两个淡水水体(芙蓉湖、厦大水库)的叶绿素浓度和遥感反射率(Rrs)进行了连续观测.在叶绿素浓度6-322mg/m3的范围,Rrs光谱出现显著的近红外反射峰,中心位置在700-710nm之间,较之通常的荧光峰中心(683nm)向长波方向偏离.该峰在厦大水库始终出现在700nm,但在芙蓉湖存在时间变化,随着叶绿素浓度的增加,由705红移到710nm.由此,仿MODIS荧光高度(FLH)的定义,定义该峰的高度(简写为REH),对于水库和美蓉湖中心波段分别确定为700和710nm.REH与叶绿素浓度呈现显著相关,美蓉湖REH=0.0161g(chl)-7.8×10-6(R2=0.79,n=41),水库REH=0.0001chl+0.0002(R2=0.74,n=32).可见对十高散射的淡水藻华水体,可以并且需要通过改进FLH的波段选择,基于更长波段处的近红外峰的高度探测叶绿素浓度.     

Erosion characteristics of loess tunnels on the Loess Plateau: A field investigation and experimental study

Loess tunnels are a common geo-hazard in the Loess Plateau and not only cause considerable soil and water loss, but also aggravate and even induce the occurrence and development of other disasters such as ground fissures, mudflows, collapses, and landslides. To date, research on the hydrological characteristics and erosion behaviour of loess tunnel systems has focused on field investigation data and limited river basin observation data, whereas field test information and data are very scarce. In this study, field surveys, observations, field scouring experiments, and laboratory-based sediment percentage tests were conducted to analyse the erosion characteristics, spatial distribution, and hydrological characteristics of a large-scale loess tunnel system in the hilly Loess Plateau southeast region of northern China. The results showed that the loess tunnel erosion exhibited periodicity. Tunnel erosion in each period shows a similar erosion process, that is, thin-layer water flow erosion and lateral expansion, tunnel wall collapse and deposit due to the loss of support from the lateral erosion, and erosion and transport of deposits by water flow. Waterfall erosion, lateral erosion, headward erosion, and the resulting collapses were the main forms of tunnel erosion. Besides this, the base level of erosion significantly affects the erosion characteristics of the loess tunnel. The hydrological characteristics during field scouring experiments exhibited three different stages: a lag effect, attributed to the temporary loss of water velocity in the first stage; small water flow fluctuations in the second stage; and an increase in total seepage loss with increased water injection flow in the third stage. The erosion rate was positively correlated with the flow quantity. The results of this study not only provide valuable reference data for research on the mechanism and velocity of erosion events in loess, but also provide a theoretical basis for the prevention of loess tunnel disasters in engineering construction. © 2020 John Wiley & Sons, Ltd.     

Quantitative estimation of submarine groundwater discharge using airborne thermal infrared data acquired at two different tidal heights

Submarine groundwater discharge (SGD) plays an important role in coastal biogeochemical processes and hydrological cycles, particularly off volcanic islands in oligotrophic oceans. However, the spatial and temporal variations of SGD are still poorly understood owing to difficulty in taking rapid SGD measurements over a large scale. In this study, we used four airborne thermal infrared surveys (twice each during high and low tides) to quantify the spatiotemporal variations of SGD over the entire coast of Jeju Island, Korea. On the basis of an analytical model, we found a linear positive correlation between the thermal anomaly and squares of the groundwater discharge velocity and a negative exponential correlation between the anomaly and water depth (including tide height and bathymetry). We then derived a new equation for quantitatively estimating the SGD flow rates from thermal anomalies acquired at two different tide heights. The proposed method was validated with the measured SGD flow rates using a current meter at Gongcheonpo Beach. We believe that the method can be effectively applied for rapid estimation of SGD over coastal areas, where fresh groundwater discharge is significant, using airborne thermal infrared surveys.     

Evaluation of the Liu model for predicting rainfall interception in forests world‐wide

Simple but effective models are needed for the prediction of rainfall interception under a full range of environmental and management conditions. The Liu model was validated using data published in the literature and was compared with two leading models in the literature: the Rutter and the Gash models. The Liu model was tested against the Rutter model on a single‐storm basis with interception measurements observed from an old‐growth Douglas fir (Pseudotsuga menziesii) forest in Oregon, USA. Simulated results by the Liu model were close to the measurements and comparable to those predicted by the Rutter model. The Liu model was further tested against the Gash model on a multistorm basis. The Gash and Liu models successfully predicted long‐term interception losses from a broad range of 20 forests around the world. Results also indicated that both the Gash and the Liu models could be used to predict rainfall interception using daily rainfall data, although it was assumed in both models that there is only one storm per rain day. The sensitivity of the Liu model to stand storage capacity, canopy gap fraction and evaporation rate from wet canopy surface during rainfall was investigated. Results indicate that the Liu model has the simplest form, least data requirements and comparable accuracy for predicting rainfall interception as compared with the Rutter and the Gash models. Copyright © 2001 John Wiley & Sons, Ltd.     

Assessment of the geometry and volumes of small surface water reservoirs by remote sensing in a semi-arid region with high reservoir density

Water fluxes in highly impounded regions are heavily dependent on reservoir properties. However, for large and remote areas, this information is often unavailable. In this study, the geometry and volume of small surface reservoirs in the semi-arid region of Brazil were estimated using terrain and shape attributes extracted by remote sensing. Regression models and data classification were used to predict the volumes, at different water stages, of 312 reservoirs for which topographic information is available. The power function used to describe the reservoir shapes tends to overestimate the volumes; therefore, a modified shape equation was proposed. Among the methods tested, four were recommended based on performance and simplicity, for which the mean absolute percentage errors varied from 24 to 39%, in contrast to the 94% error achieved with the traditional method. Despite the challenge of precisely deriving the flooded areas of reservoirs, water management in highly reservoir-dense environments should benefit from volume prediction based on remote sensing.     

Variation in the sediment deposition behind check‐dams under different soil erosion conditions on the Loess Plateau,China

To maintain a reasonable sediment regulation system in the middle reaches of the Yellow River, it is critical to determine the variation in sediment deposition behind check‐dams for different soil erosion conditions. Sediment samples were collected by using a drilling machine in the Fangta watershed of the loess hilly–gully region and the Manhonggou watershed of the weathered sandstone hilly–gully (pisha) region. On the basis of the check‐dam capacity curves, the soil bulk densities and the couplet thickness in these two small watersheds, the sediment yields were deduced at the watershed scale. The annual average sediment deposition rate in the Manhonggou watershed (702.0 mm/(km²·a)) from 1976 to 2009 was much higher than that in the Fangta watershed (171.6 mm/(km²·a)) from 1975 to 2013. The soil particle size distributions in these two small watersheds were generally centred on the silt and sand fractions, which were 42.4% and 50.7% in the Fangta watershed and 60.6% and 32.9% in the Manhonggou watershed, respectively. The annual sediment deposition yield exhibited a decreasing trend; the transition years were 1991 in the Fangta watershed and 1996 in the Manhonggou watershed (P < 0.05). In contrast, the annual average sediment deposition yield was much higher in the Manhonggou watershed (14011.1 t/(km²·a)) than in the Fangta watershed (3149.6 t/(km²·a)). In addition, the rainfalls that induced sediment deposition at the check‐dams were greater than 30 mm in the Fangta watershed and 20 mm in the Manhonggou watershed. The rainfall was not the main reason for the difference in the sediment yield between the two small watersheds. The conversion of farmland to forestland or grassland was the main reason for the decrease in the soil erosion in the Fangta watershed, while the weathered sandstone and bare land were the main factors driving the high sediment yield in the Manhonggou watershed. Knowledge of the sediment deposition process of check‐dams and the variation in the catchment sediment yield under different soil erosion conditions can serve as a basis for the implementation of improved soil erosion and sediment control strategies, particularly in semi‐arid hilly–gully regions. Copyright © 2018 John Wiley & Sons, Ltd.     

Impact of interacting bark structure and rainfall conditions on stemflow variability in a temperate beech-oak forest,central Germany

ABSTRACT

Trees concentrate rainfall to near-stem soils via stemflow. When canopy structures are organized appropriately, stemflow can even induce preferential flow through soils, transporting nutrients to biogeochemically active areas. Bark structure significantly affects stemflow, yet bark-stemflow studies are primarily qualitative. We used a LaserBark to compute bark microrelief (MR), ridge-to-furrow amplitude (R) and slope (S) metrics per American Society of Mechanical Engineering standards (ASME-B46.1–2009) for two morphologically contrasting species (Fagus sylvatica L. (European beech), Quercus robur L. (pendunculate oak)) under storm conditions with strong bark water storage capacity (BWSC) influence in central Germany. Smaller R and S for F. sylvatica significantly lowered BWSC, which strongly and inversely correlated to maximum funnelling ratios and permitted stemflow generation at lower rain magnitudes. Larger R and S values in Q. robur reduced funnelling, diminishing stemflow drainage for larger storms. Quercus robur funnelling and stemflow was more reliant on intermediate rain intensities and intermittency to maintain bark channel-dependent drainage pathways. Shelter provided by Q. robur’s ridged bark also appears to protect entrained water, lengthening mean intrastorm dry periods necessary to affect stemflow. Storm conditions where BWSC plays a major role in stemflow accounted for much of 2013’s rainfall at the nearest meteorological station (Wulferstedt).

Editor M.C. Acreman; Associate editor not assigned