Landscape Hydrology Research Articles

Role of hydro-geochemical functions on karst critical zone hydrology for sustainability of water resources and ecology in Southwest China

Focusing on sustainability of water resources and ecology in the complex karst critical zone, we illustrated functions of the hydro-geochemical analysis on hydrology from the aspects of connection and interaction among hydrology–vegetation–soils/rock fractures along the karst subsurface profile. We reviewed isotopic and geochemical interpretations on tracing water sources for plant uptake, quantifying watershed outlet flow composition and residence times, and evaluating long-term evolution among climate–landscape–hydrology in the karst critical zone. In this paper, the application of the hydro-geochemical analysis on the above aspects in the karst areas of southwest China was summarized.

Hydrologic Landscape Classification to Estimate Bristol Bay, Alaska Watershed Hydrology

AbstractHydrologic landscapes (HLs) have proven to be a useful tool for broad scale assessment and classification of landscapes across the United States as they help organize larger geographical areas into areas of similar hydrologic characteristics. We developed a HL classification for the Bristol Bay watershed of southwest Alaska that incorporates indices of annual climate and seasonality, terrain, geology, and the influences of large lakes and glaciers. A HL classification is particularly useful in this large watershed because of its hydrologic and landscape variability, important salmon fishery, variety of environmental and potential anthropogenic stressors, and lack of widespread hydrologic data. Following creation of Bristol Bay basin‐wide HL classes, we compared the HL distributions within watersheds grouped by two calculated runoff parameters derived from available long‐term streamflow records and found HL distributions within these groups provided predictive insight on hydrologic behavior. Using these developed runoff groups, we estimated expected hydrologic behavior in watersheds across the larger Bristol Bay watershed that lacked gauged streamflow records. The HL approach provides a scientific basis for estimating the first‐order hydrologic behavior of watersheds and landscapes that lack detailed hydrologic information.

Tuning the physicochemical properties of biochar derived from Ashe juniper by vacuum pressure and temperature

Ashe juniper is a problematic plant in central Texas due to rapid expansion causing the alteration of rangeland plant communities and hydrological landscapes. The thermochemical conversion of Ashe juniper into biochar with specific properties is a promising option for valorization of Ashe juniper. This study presents the effects of temperature (350, 450 and 520°C) and vacuum pressure (0.09, 0.7 and 3kPa) on physical and chemical properties of biochar produced by vacuum pyrolysis from Ashe juniper. We found that temperature had a major effect on the degree of carbonization and surface functionality, as well as the O/C and H/C ratios regardless of vacuum pressure. It was determined that the effect of vacuum pressure severity on product properties depends on pyrolysis temperature. In addition, the vacuum pressure was a crucial factor for controlling the surface area and porosity at each constant pyrolysis temperature. This work also demonstrated that the biochar from Ashe juniper under vacuum pyrolysis showed improved aromaticity and surface area compared to the biochar derived from other biomass. Biochar produced at 450 and 520°C showed potential application as an adsorbent, a catalyst support and a carbon sequestration agent. Methylene blue (MB) adsorption test confirmed that biochar produced at 450°C and 0.7kPa showed potential as an adsorbent.

Development of Regional Curves for Hydrologic Landscape Regions (HLR) in the Contiguous United States

AbstractRegional curves relate drainage area to the bankfull channel characteristics discharge, cross‐sectional area, width, and mean depth. These curves are used for a variety of purposes, including aiding in the field identification of bankfull elevation and in the natural channel design process. When developing regional curves, the degree to which landform, geology, climate, and vegetation influence stream systems within a single physiographic province may not be fully considered. This study examined the use of the U.S. Geological Survey's Hydrologic Landscape Regions (HLR), as well as data from 2,856 independent sites throughout the contiguous United States (U.S.), to develop a set of regional curves (bankfull discharge, cross‐sectional area, width, and mean depth) for (1) the contiguous U.S., (2) each of the 20 HLRs, (3) each of the eight physiographic divisions, (4) 22 of the 25 physiographic provinces, and (5) individual HLRs within the physiographic provinces. These regional curves were then compared to each other, as well as those from the literature. Regional curves developed for individual HLRs, physiographic divisions, and physiographic provinces tended to outperform the contiguous U.S. indicating increased stratification was beneficial. Further stratifying physiographic provinces by HLR markedly improved regional curve reliability. Use of HLR as a basis of regional curve development, rather than physiographic region alone, may allow for the development of more robust regional curves.

The hydrologic landscape of the Ajó coastal plain, Argentina: An assessment of human-induced changes

Abstract Coastal wetlands rank among the most endangered ecosystems since they are affected by the sea level rise and by anthropogenic activities. The continued loss and degradation of these valuable environments requires greater understanding of groundwater–surface water exchange, as the ecological function of coastal wetlands greatly depends on it. Hydrological research carried out in the lower part of the Samborombon Bay coastland (Rio de la Plata estuary, Argentina) by remote sensing revealed the presence of a meandering channel system, which does not appear in modern maps. Analysis of SPOT satellite images and interpretation of historical maps and in situ surveys confirmed that this structure is part of an ancient river system – the palaeo-Rincon de Ajo River – at present almost completely silted up. In addition, multispectral satellite data provided information to develop a conceptual hydrological model, as well as evidence that a significant hydrologic landscape shift occurred due to human-made interventions. The palaeo-Rincon de Ajo River disappeared because water flow in its upper course was intercepted by human-made canals. In its lower course, embankments built for the construction of roads and flood prevention of the wetlands from the Rio de la Plata estuary excluded the surface flow from the estuary to the mainland and vice versa. The silting up in the lower course and in the vicinity of the mouth cancelled the original structure of the ancient river.

DAMPAK PARIT DRAINASE TERHADAP TINGGI MUKA AIR, KONDISI TANAH DAN PERTUMBUHAN POHON DI HUTAN GAMBUT KALIMANTAN BARAT

Currently, tropical peatland forests are under considerable pressure because of increasing deforestation and degradation of forests. In Kalimantan, degradation and deforestation of peatland forests are driven primarily by industrial logging, expansion of agricultural activities through primarily conversion of forests to agricultural land and oil palm plantations. By the establishment of intensive drainage, it can induce wildfires in peatland. Unmanaged drainage ditches will alter water table levels within the site adjacent to the drainage including to surrounding peatland forest. Water table assessments were conducted before and after peatland drainage on 2007/2009 and 2012/2015 in Kubu Raya, West Kalimantan. This paper studies the effect of drainage ditches into the peatland water table. Results show the establishment of drainage ditches on this peatland landscape lowered the water table by more than 3 times from ~11.7 cm (SE = 1.5, n = 5) to ~37.3 cm (SE = 2.1 cm, n = 26). The effect on the water table was in drier months of July-August. Lowering the water table level altered worst the soil micro climate, peat temperature and peat water content. The results indicate the land use changes in peatland with the establishment of drainage affects peatland water table currently. In the area of less than 500 m from the drainage, the water level tends to lower toward the drainage feature. Therefore, recovery of peatland forests should be initiated by managing the landscape hydrology (i.e. water table) to restore the ecosystem and to protect the remaining peat swamp forest.

Water tracks in the High Arctic: a hydrological network dominated by rapid subsurface flow through patterned ground

Water tracks play a major role in the headwater basin hydrology of permafrost landscapes in Alaska and Antarctica, but less is known about these features in the High Arctic. We examined the physical and hydrological properties of water tracks on Ward Hunt Island, a polar desert site in the Canadian High Arctic, to evaluate their formation process and to compare with water tracks reported elsewhere. These High Arctic water tracks flowed through soils that possessed higher near-surface organic carbon concentrations, higher water content, and coarser material than the surrounding soils. The water track morphology suggested they were initiated by a combination of sorting, differential frost heaving, and eluviation. The resultant network of soil conduits, comparable to soil pipes, dominated the hydrology of the slope. The flow of cold water through these conduits slowed down the progression of the thawing front during summer, making the active layer consistently shallower relative to adjacent soils. Water tracks on Ward Hunt Island, and in polar desert catchments with these features elsewhere in the High Arctic, strongly influence slope hydrology and active-layer properties while also affecting vegetation distribution and the quality of runoff to the downstream lake.

The basin concept: From hydrology to nature management

The main development stages of the basin concept: from landscape hydrology to nature management are considered. It is shown that the river, lake and sea drainage basins are the most widespread natural complexes on and surface, with a high degree of integrity and with clear-cut watershed divides having a powerful integrating factor, the water flow. The substantiation is provided for the concepts of the basis as a geosystem, the runoff-producing complexes and the hydrological functions of landscape as well as for the principles of hydrological, water-resources and water-protection regionalization and zoning. On this basis, a classification of hazardous hydrological processes is developed. The structural patterns of the river network within the framework of structural geography are used for indication of the mean long-term discharge and its mapping, and for a classification of river systems according to their size. It is demonstrated that the integrating properties of the water flow permit the basin to be regarded as an integral system entity not only from the perspective of hydrology but also in terms of geomorphology, biogeocenology, landscape geochemistry as well as in complex physical geography as functionally integral natural complexes thereby creating the natural basis for nature management. On the other hand, many basins are socioeconomic and ethnodemographic entities. Ten principles are formulated for the theoretical justification of the basin concept of nature management where the basin is treated as an integral natural and economic system. It is suggested that such an approach should be used in governance of nature management, especially in international basins, as well as in reforming the system of administrative-territorial division of Russia.

Forensic hydrology: what function tells about structure in complex settings

Facing the challenges of the European Water Framework Directive and competing demands requires a sound knowledge of the hydrological system. This is a major challenge in regions like Northeast Germany. The landscape has been massively reshaped during repeated advances and retreats of glaciation during the Pleistocene. This resulted in a complex setting of unconsolidated sediments with high textural heterogeneity and with layered aquifer systems, partly confined, but usually of unknown number and extent of single aquifers. The Institute of Landscape Hydrology aims both at a better understanding of hydrological processes and at providing a basis for sustainable water resources management in this region. That would require sound information about the respective regions of interest that are rarely available at sufficient degree of detail. Thus, there is urgent need for alternative approaches. For example, time series of groundwater head, lake water level and stream runoff do not only depend on (unknown) geological structures, but in turn can reveal information about major geological features. To that end, different approaches have been developed and successfully applied at different scales, based both on advanced time series analysis and dimension reduction approaches and on well-known and rather simple methods. This approach has been coined “forensic hydrology”: Like in a crime story, numerous pieces of evidence are combined in a systematic way to end up with a consistent conceptual model about the prevailing cause–effect relationships. An example is given for the Quillow catchment in Northeast Germany in a rather complex geological setting.

A GIS based approach to Holocene hydrology and social connectivity in the Gobi Desert, Mongolia

This paper presents the results of a GIS derived drainage network, demonstrating a hypothesized model of the Ulaan Nuur paleo hydrological system in the Gobi Desert of Mongolia. Furthermore, this model was successfully used as a basis for field survey along the hypothesized southern edge of the paleo lake and associated paleo channels, which led to the discovery of four Neolithic period sites, several Neolithic surface scatters, and one later period cemetery. This allows for the establishment of a potential, viable route of movement between the Gobi Altai and Bayanzag, along the southern paleo hydrological system of Ulaan Nuur. This case study further demonstrates that through examination of paleo hydrological landscapes in the Gobi Desert, GIS hydrology modelling may provide a reliable methodology to locate sites in other arid and semi-arid environments, and enable further evaluation of their relationships to past watercourses.

Communicating landscape hydrology — the water cycle in a box

AbstractPhysical models are a well‐established tool in education to strengthen hydrological understanding. They facilitate the straightforward visualization of hydrological processes and allow the communication of hydrological concepts, research and questions of general interest to the public. In order to visualize the water cycle in a landscape of postglacial sediments, in particular the subsurface part, a physical model was constructed. In two videos, (1) a detailed construction manual and (2) visualization examples of hydrological concepts and processes are presented. With our contribution, we like to encourage professionals in the field of hydrology to share methods and tools of knowledge transfer and communication of hydrological concepts. Copyright © 2016 John Wiley & Sons, Ltd.

Delineation of Environmental Units by Multivariate Techniques in the Duero River Watershed, Michoacán, Mexico

Environmental or hydrological landscape units can integrate various environmental characteristics to support proper management of natural resources. To delineate these units, quantitative methods such as ordination, clustering, and classification of abiotic factor information are used. In the present work, environmental units were delineated in the Duero River watershed of Michoacan, Mexico. This will enhance understanding of the hydrologic landscape, which is a fundamental to natural resource management. A digital elevation model was used to generate sub-basins. Climatic data were obtained from 16 meteorological stations. Sixty-nine soil and 150 water samples were collected and analyzed in the laboratory. Geostatistical methods for spatial prediction of the environmental variables were used. Mean data for each sub-basin were obtained from the environmental variable grids, generating an abiotic factor data matrix. A multivariate analysis was conducted. Exponential, linear, spherical, and Gaussian models were fit to an empirical variogram. Spatial prediction of the environmental data was done via universal and ordinary kriging. Based on principal component analysis, abiotic factors evaporation, total nitrogen, soil pH, and sodium absorption ratio of water were selected for cluster analysis. Five environmental units were delineated in the Duero watershed. One environmental unit (number 4) provided greater than 50 % of the payment for ecosystem services. The general trend is an increase of urban area. The urban surface in 1983 and 2014 was 1724 and 4750 ha, respectively, an increase of 275 %. Environmental unit 1 showed the greatest urban area growth (1336 ha) during the latter period.

Nature-inspired stormwater management practice: The ecological wisdom underlying the Tuanchen drainage system in Beijing, China and its contemporary relevance

There are many outstanding constructions in ancient Chinese cities that are still in use in their unique local landscapes. An example of successful ecological engineering is the Tuancheng drainage system in Beijing. This paper presents a technical analysis of this drainage system and describes a hydrological model built in Stella® for a one-time rainstorm event and for annual water balance analyses. The results demonstrate how well the drainage criteria were chosen and prove that the implementation was exceptionally successful. An example of smart design solutions is the underground circular C-shaped drainage system in the terrace, where at each turning point, there is a pit to collect rainwater. In addition, the inverted paving by trapezoidal bricks and soil improvements contributed to the rapid infiltration of rainwater. During intense rainstorms, the system effectively attenuated stormwater and increased the infiltration rate. During drought conditions, such as in 1965, with only 226mm of rainfall, the system increased soil water retention by 27mm. The Tuancheng drainage system is an excellent example of an engineering solution managing drainage and storage, on- and underground, and using gray and green infrastructure to create a hydrological landscape functionally equivalent to natural conditions. Exploring ancient wisdom and using the ideas of our ancestors can help us to find more effective and efficient strategies to manage urban stormwater.

An approach to maintaining hydrological networks in the face of land use change

Ephemeral drainage patterns in the prairie pothole region of southern Alberta are not well understood at the landscape level. Municipal land use planning generally places very few constraints on development, which can leave the existing landscape topography and drainage patterns highly modified and engineered. Few if any features that exist within the pre-development landscape remain post-development. Part of the residential or industrial land development process is the creation of master drainage plans which focus on collecting and moving precipitation or snow melt away from roads and buildings through drainage ponds and piping systems. However, in prairie pothole landscapes, there is a landscape hydrology system that connects wetlands and sub-surface soil moisture flows and involves significant ephemeral components. These existing landscape flow systems provide ecosystem services in both flood and drought conditions. However, conventional land conversion processes do not generally recognize existing landscape processes like hydraulic connectivity in the development process. This creates a gap between the standard engineering approach and landscape structure and function which puts landscape processes and services at risk of being lost over time. The method demonstrated in this paper has been designed to bridge pre-development and post-development conditions for hydrologic flow systems. This method can be used as an additional cross-scalar information “layer” for use in the planning process to identify how utilities, roads and building sites can be spatially organized to complement rather than conflict with existing landscape flow systems in areas with minimal topographic relief and specifically in Prairie Pothole Region landscapes. This relatively simple technique can help reduce infrastructure costs and enables development to maintain natural flow systems and cross-scalar hydraulic connectivity.

Tolerance of Elevated Ozone and Water Stress in a California Population of Palmer Amaranth (Amaranthus palmeri)

Palmer amaranth is a highly invasive weed species causing huge economic losses in agricultural cropping systems under a broad range of environmental conditions. Sensitivity of this species to ozone (O3) air pollution and to soil water deficit, relative to native species or competing crops, may affect its competitiveness and invasive potential. In recent years, both high tropospheric O3and soil water deficiency have become common in the San Joaquin Valley of California. Responses to these environmental parameters may help predict the invasiveness of this species and have implications for landscape hydrology. We assessed the impact of O3and soil water deficit on Palmer amaranth. Five- to seven-leaf–stage potted plants were placed in continuous stirred tank reactor chambers and maintained for 30 to 35 d under 12-h mean daylight O3exposures (0700–1900 hours) of 4, 59, or 114 ppb O3. Within the chambers the plants were either well-watered (WW) or exposed to regulated deficit irrigation (RDI) and grown for about 7 wk. Dry weights of the leaves, stems, roots, and leaf area were determined. Day- and nighttime stomatal conductances (gs) were measured at 1.5-h intervals. Nocturnalgswas about 16 to 29% of daytimegs; this suggests that the species could have substantial nighttime water loss, uncoupled from carbon gain in the weed, and could affect water availability for crops and reduce irrigation efficiency. Nocturnalgswas lower in the RDI than in the WW, but daytimegswas not affected by O3or irrigation regime. Neither O3nor irrigation regime affected root or shoot parameters. As O3and drought are two key stressors in the San Joaquin Valley, to which potential competing species have been found to be sensitive, Palmer amaranth may proliferate and become more invasive in the future, potentially altering landscape hydrology and reducing irrigation efficiency.

Evidence of multiple thermokarst lake generations from an 11 800‐year‐old permafrost core on the northern Seward Peninsula, Alaska

Permafrost degradation influences the morphology, biogeochemical cycling and hydrology of Arctic landscapes over a range of time scales. To reconstruct temporal patterns of early to late Holocene permafrost and thermokarst dynamics, site‐specific palaeo‐records are needed. Here we present a multi‐proxy study of a 350‐cm‐long permafrost core from a drained lake basin on the northern Seward Peninsula, Alaska, revealing Lateglacial to Holocene thermokarst lake dynamics in a central location of Beringia. Use of radiocarbon dating, micropalaeontology (ostracods and testaceans), sedimentology (grain‐size analyses, magnetic susceptibility, tephra analyses), geochemistry (total nitrogen and carbon, total organic carbon, δ13Corg) and stable water isotopes (δ18O, δD, d excess) of ground ice allowed the reconstruction of several distinct thermokarst lake phases. These include a pre‐lacustrine environment at the base of the core characterized by the Devil Mountain Maar tephra (22 800±280 cal. a BP, Unit A), which has vertically subsided in places due to subsequent development of a deep thermokarst lake that initiated around 11 800 cal. a BP (Unit B). At about 9000 cal. a BP this lake transitioned from a stable depositional environment to a very dynamic lake system (Unit C) characterized by fluctuating lake levels, potentially intermediate wetland development, and expansion and erosion of shore deposits. Complete drainage of this lake occurred at 1060 cal. a BP, including post‐drainage sediment freezing from the top down to 154 cm and gradual accumulation of terrestrial peat (Unit D), as well as uniform upward talik refreezing. This core‐based reconstruction of multiple thermokarst lake generations since 11 800 cal. a BP improves our understanding of the temporal scales of thermokarst lake development from initiation to drainage, demonstrates complex landscape evolution in the ice‐rich permafrost regions of Central Beringia during the Lateglacial and Holocene, and enhances our understanding of biogeochemical cycles in thermokarst‐affected regions of the Arctic.

Influences and interactions of inundation, peat, and snow on active layer thickness

AbstractActive layer thickness (ALT), the uppermost layer of soil that thaws on an annual basis, is a direct control on the amount of organic carbon potentially available for decomposition and release to the atmosphere as carbon‐rich Arctic permafrost soils thaw in a warming climate. We investigate how key site characteristics affect ALT using an integrated surface/subsurface permafrost thermal hydrology model. ALT is most sensitive to organic layer thickness followed by snow depth but is relatively insensitive to the amount of water on the landscape with other conditions held fixed. The weak ALT sensitivity to subsurface saturation suggests that changes in Arctic landscape hydrology may only have a minor effect on future ALT. However, surface inundation amplifies the sensitivities to the other parameters and under large snowpacks can trigger the formation of near‐surface taliks.

Dynamics of mine rocks and artificial soils agrochemical characteristics under the impact of long-term reclamation

The agrochemical characteristics of mine rocks and artificial soils of forest recultivation plot № 1 of «Pavlogradska» mine were studied. The quantitative indicators of humus, phosphorus, potassium and nitrogen content of the soil and mine rocks samples were described. Changes of agrochemical characteristics of mine rocks and artificial soils, that occur as a result of long-term reclamation and exert an impact on forests suitability and silvicultural effect, were ascertained. Variants of artificial soils, created on the experimental forest recultivation plot, have qualitative differences from natural etalon soils, disturbed soils and differences between themselves. During the creation of various soil constructions in the process of recultivation it is often not taken into account the possible distant consequences that arise in connection with the dynamic features of the climate, topography, lithology, hydrology and other indicators of technogenic landscapes. Due to the functioning of these soil constructions there are significant changes in physical properties and processes, occurring in the remediation root layer, therefore there are a number of issues related to the further evolution of these structures. In this connection a studying of properties and processes in the artificial soils and an analysis of its current state and evolution prognosis become relevant, with a glance of targeted orientation of recultivation layer constructs and characteristics of specific conditions. The aim of the research is an investigation of agrochemical characteristics of bulk soils and an assessment of its forests suitability on the forest recultivation plot of «Pavlogradska» main, with an area of 3.2 hectares, where different constructions of forest plantations are being tested since 1976 on the different versions of artificial soils. The novelty of the work lies in that the findings show the dynamics of artificial soils properties under the influence of long-term biological remediation measures. The humus state of a soil is a complex of morphological traits, common stocks, properties of organic matter and processes of its creation, transformation and migration in the soil profile. This is a fundamental property of soil because it determines the variety of fertility factors. The content of organic matter in mine rocks and artificial soils ranges from 0,15±0,02 (sand) to 6,25±0,08 % (mine rock). However despite the fact that the amount of organic matter in the mine rocks is high, it is a part of the denatured organic compounds, which are not available for free mineralization. Nitrogen is a necessary element for plant development and its soil content determines the level of soil fertility. The analysis showed that the amount of nitrogen ranges from very low in mine rocks to heightened in chernozem loams. The most important biogenic elements also include phosphorus and potassium, which are essential nutrients for plants. Phosphorus and potassium availability is ranging from low in mine rocks to very high in chernozem loams. Also a decrease of potassium and phosphorus content down the soil profile is observed in different artificial soil variants, which correlates with a decrease of plant roots quantity with depth. The most relevant area of recultivation for steppe zone is forestry, in which environmentally hazardous areas are planted with reclamation forest cultures. However, it should be taken into account that creation of artificial forests in steppe zone is a measure associated with certain difficulties, particularly on the zonal chernozem soils. Even greater difficulties encountered in anthropogenic degradation of a substrate with a deterioration of its physicochemical and agrochemical properties in industrial use of lands, which should be considered in the forest land reclamation.

Hydrologic Landscape Characterization for the Pacific Northwest, USA

AbstractWe update the Wigington et al. (2013) hydrologic landscape (HL) approach to make it more broadly applicable and apply the revised approach to the Pacific Northwest (PNW; i.e., Oregon, Washington, and Idaho). Specific changes incorporated are the use of assessment units based on National Hydrography Dataset Plus V2 catchments, a modified snowmelt model validated over a broader area, an aquifer permeability index that does not require preexisting aquifer permeability maps, and aquifer and soil permeability classes based on uniform criteria. Comparison of Oregon results for the revised and original approaches found fewer and larger assessment units, loss of summer seasonality, and changes in rankings and proportions of aquifer and soil permeability classes. Differences could be explained by three factors: an increased assessment unit size, a reduced number of permeability classes, and use of smaller cutoff values for the permeability classes. The distributions of the revised HLs in five groups of Oregon rivers were similar to the original HLs but less variable. The improvements reported here should allow the revised HL approach to be applied more often in situations requiring hydrologic classification and allow greater confidence in results. We also apply the map results to the development of hydrologic landscape regions.

Delineation and Quantification of Wetland Depressions in the Prairie Pothole Region of North Dakota

The Prairie Pothole Region of North America is characterized by numerous, small, wetland depressions that perform important ecological and hydrological functions. Recent studies have shown that total wetland area in the region is decreasing due to cumulative impacts related to natural and anthropogenic changes. The impact of wetland losses on landscape hydrology is an active area of research and management. Various spatially distributed hydrologic models have been developed to simulate effects of wetland depression storage on peak river flows, frequently using dated geospatial wetland inventories. We describe an innovative method for identifying wetland depressions and quantifying their nested hierarchical bathymetric/topographic structure using high-resolution light detection and ranging (LiDAR) data. This contour tree method allows identified wetland depressions to be quantified based on their dynamic filling-spilling-merging hydrological processes. In addition, wetland depression properties, such as surface area, maximum depth, mean depth, storage volume, etc., can be computed for each component of a depression as well as the compound depression. We successfully applied the proposed method to map wetland depressions in the Little Pipestem Creek watershed in North Dakota. The methods described in this study will provide more realistic and higher resolution data layers for hydrologic modeling and other studies requiring characterization of simple and complex wetland depressions, and help prioritize conservation planning efforts for wetland resources.