Terrestrial ecosystems of the conterminous united states. Highresolution global topographic index values for use in large. Widespread negative correlations between black spruce growth and temperature across topographic moisture gradients in the boreal forest. Suppixel, digital elevation model dem, spatial resolution, attraction models, topographic wetness index twi, gis. I would like to know how we can determine soil moisture index values from reflectance values in landsat tm images. Sensitivity of the enhanced vegetation index evi and normalized. Three future scenarios represent different assumptions about the rate of future climate change. This may be useful when attempting to model ancient environments. Topsoil moisture maps the cpc produces top soil maps based on the usda data. Utilizing a topographic moisture index to characterize. The application of the approach does not involve subjective categorization of topographic variables, so that results should be uniform between users.
Twi has more details from the moisture of soil than the twi map prepared with dem 90m. Thus it can provide indirect information on land cover and agricultural potential. One approach to quantify this control is the topographic lnatanb index. Depthtowater is an index of relative site moisture derived from the wet areas mapping tool using a finescale digital elevation model based upon remotelysensed lidar light detection and ranging data.
The climate moisture index provides an index of moisture available to support plant growth on an annual basis. For more information, download our soil moisture manuscript. On the calculation of the topographic wetness index. Topographic relative moisture index how is topographic. The study area was subdivided into 120 locations consisting. It is commonly used to quantify topographic control on hydrological processes. Moisture mapping and moisture diagram are terms commonly used in geology, climate forecasting, meteorology, farming, grain storage and kiln drying to describe the moisture content, movement or changes in moisture. Jiang1,2 1 key laboratory of mountain hazards and surface process, chinese academy of sciences, chengdu610041, china.
The index is a function of both the slope and the upstream contributing area per unit width orthogonal to the flow direction. Introduction soil moisture is a key variable controlling hydrological and biogeochemical processes. Runoff response to soil moisture and micro topographic structure on the plot scale. Generally, however, soil moisture is the water that is held in the spaces between soil particles. This study adds soil depth and soil texture parameters to the slope parameters of the trmi, thereby creating the relative site moisture index rsmi. Assessing landscape conditions relative to water resources in the western united states. Through its control on soil moisture patterns, topographys role in influencing forest composition is widely recognized. Download citation the topographic relative moisture index. A new topographic index to quantify downslope controls on local drainage k.
In general, the differences are small, and in some cases even insignificant. Getting negative topographic wetness index twi values in. This study quantifies the effects of topographic aspect on surface fine fuel moisture content ffmc in order to better represent landscapescale variability in fire risk. Compound topographic index anthropology analytical. Discussion on using antecedent precipitation index to supplement relative soil moisture data series y.
Surface soil moisture is the water that is in the upper 10 cm of. Potential runoffcontributing areas were estimated collectively for the processes of infiltrationexcess and. Additionally, the index was generally extracted from. The results were used to compare 91 selected subbasins representing slope, soil, landuse, and runoff variability across the state. Trmi is defined as topographic relative moisture index ecology somewhat frequently. Use of site water balance metrics such as the topographic relative moisture index trmi or topographic wetness index twi can be helpful in identifying. For the purpose of informing biodiversity conservation efforts in managed landscapes, we explored whether and how understory plant communities abundance, diversity, composition were related to a topographic moisture index, called depthtowater, in the boreal mixedwood forests of northwestern alberta. Geological survey has generated topographic moisture potential classes to be used in creating maps depicting standardized, terrestrial ecosystem models for the conterminous united states, using an ecosystems classification developed by natureserve. Moisture mapper is a cloudbased solution that provides professional restorers with a platform for documenting and reporting on any water mitigation project. Utilizing a topographic moisture index to characterize understory vegetation patterns in the boreal forest. Abstract differences in soil properties were found between north and southfacing slopes located in a mediterranean region with an average annual rainfall of 690 mm.
According to nasas earth science office, soil moisture means different things in different disciplines. Using topographic wetness index in vegetation ecology. From these measurements, soil water potential, fractional water index and volumetric water can be derived. Terrestrial ecosystemstopographic moisture potential of. Dpe, where im is the moisture index, s is the water surplus in months when precipitation exceeds evapotranspiration d is the water deficit in months when. Use of site water balance metrics such as the topographic relative moisture index trmi or topographic wetness index twi can be helpful in identifying underlying moisture gradients that.
The data used to create the maps and regional data that include the northern us are also available for download. The topographic relative moisture index trmi, was developed as a tool for estimating relative soil moisture conditions in mountainous terrain using only slope characteristics. Topographic position and landforms analysis the nature. Topographic relative moisture index how is topographic relative moisture index abbreviated. Moisture mapper simplifies the documentation process that supports your drying strategy and substantiates the resulting invoice. Hi, as far as i understand the peuckerdouglas methode to identify surface specific points only analyses the 8 surrounding cells of the dem. And the terrain position was graded by a function of relative position index rpi. Trmi stands for topographic relative moisture index ecology. Relative contribution of the topographic influence on the. Check soil moisture conditions at the daily and monthly scale. The soil moisture content was somewhat greater at the lms sites 11. All of the topographic data used for this assessment was derived from the usgs 30meter ned including the national compound topographic index. The integrated moisture index imi, a gisderived index categorizing landscape into three moisture regimes, was related to many of the measured variables.
The topographic relative moisture index trmi, designed to indicate the relative soil moisture availability among sites in mountain terrain, is described. The heterogeneity of vegetation types was estimated with simpsons diversity index d. Estimation and comparison of potential runoffcontributing. How is topographic relative moisture index ecology abbreviated. The correlation of topographicallyderived relative.
Structural equation modelling sem was used to explore the relationships between the spatial characteristics of vegetation and three predictor variables. An approach to soilmoisture assessment in mountain terrain the topographic relative. Chapter 3 a gisderived integrated moisture index northern. Moisture index a term based on the computation of an annual moisture budget by c. Moisture diagrams and moisture mapping are also commonly used and sometimes.
An improved topographic wetness index considering topographic. A farmers concept of soil moisture is different from that of a water resource manager or a weather forecaster. Topographic controls on snow distribution, soil moisture. Not all negative values, but the minimum of the twi range is negative for some steep watersheds we are examining. The data is provided in graphical and tabular formats, for the contiguous united states. Discussion on using antecedent precipitation index to. Relationship between topography and soil moisture 30 2. Runoff response to soil moisture and microtopographic structure on the plot scale. The spatial distribution of vegetation types in the. Beaty and taylor 2001 used a topographic relative moisture index to study spatial and temporal variations in fire regimes in a mixed conifer forest landscape, including a giant sequoia community. The topographic wetness index twi is frequently used to simulate the soil moisture conditions in a watershed quantitatively, and it is the most commonly used indicator for static soil moisture content as well. A gisderived integrated moisture index to predict forest. Comeau, barry white, linking the depthtowater topographic index to soil moisture on boreal forest sites in alberta, forest science, volume 62, issue 2, april 2016.
I came across the topographic position index by weiss, where the relative position of a raster cell is analysed by comparing its elevation to the average elevation of all cells within a user defined radius ex. Utilizing a topographic moisture index to characterize understory. This index is therefore a relative measure of the longterm soil moisture. So it plays an important role in the research of soil erosion and distributed hydrological model in watersheds, etc. Linking the depthtowater topographic index to soil. Topographic relative moisture index trmi, developed by albert parker, uses only slope. The amount of organic matter, na, cl, and k, and available nitrogen nnh4 and nno3 are higher in the northern. The calibrated change in temperature of the soil over time after a heat pulse is introduced. Halpin 1995 identified 75 sequoia groves within the vicinity of seki. The palmer drought severity index pdsi and crop moisture index cmi are indices of the relative dryness or wetness affecting water sensitive economies. However, there were no intercomparison analyses of the twi for the 75 groves. The topographic wetness index twi is frequently used to simulate the soil moisture conditions in a watershed quantitatively, and it is the most commonly used indicator for static soil moisture.
The topographic position index tpi compares the elevation of each cell in a dem to the mean elevation of a specified neighborhood around that cell fig. This research has been tried to evaluate the spatial and temporal variability of surface soil moisture sm in a semiarid and cold region of ardabil province in iran with an area of about 10,000 km2. This method does not use climate or soil attributes to calculate relative topographic moisture potential since these characteristics are incorporated into the ecosystem model though other input layers. The topographic wetness index twi, also known as the compound topographic index cti, is a steady state wetness index. The first predictor variable was the average wind shelter. Digital topographic, soil, and landuse information was used to estimate potential runoffcontributing areas in kansas.
Vadose zone journal original research moisture stress. Spatial and temporal variability of soil moisture in. The used sm data is the smap enhanced l2 radiometer halforbit 9 km soil moisture, provided by nasa. Assessing topographic patterns in moisture use and stress. I am getting negative topographic index wetness values in saga gis anyone else every get this. Pdf quantifying the effects of topographic aspect on. Since moisture and topography influence vegetation patterns, we. Topographic relative moisture index listed as trmi. Surface ffmc in a eucalypt forest was measured from december to may 180 days.
The amount of organic matter, na, cl, and k, and available nitrogen nnh4 and nno3 are higher in the northern aspect than in the southern one. Depthtowater is an index of relative site moisture derived from the. This study addresses shortcomings in traditional moisture indices by employing a water balance approach, incorporating topographic and edaphic variability to assess finescale moisture demand and moisture availability. Soil moisture conditions at the daily and monthly scales depicting total soil moisture, percentiles and anomalies, as well as monthly and seasonal change. To test whether presence and abundance of oregon terrestrial mollusks could be explained in part by different levels of relative soil moisture, we examined survey data from the tillamook blm for correlation with relative wetness as measured by the topographic wetness index see methods, and through geomorphic features that captured different.
132 1331 1201 156 950 549 690 1203 54 1319 1457 536 1126 153 729 457 279 1001 237 332 982 1525 53 1384 671 1377 518 427 351 1056 34 620 514 455 946 399 1253 1312 967 1306 1488 171 111 985 301 470 8 1336