Canopy interception is the rainfall that is intercepted by the canopy of a tree and successively evaporates from the leaves. Precipitation that is not intercepted will fall as throughfall or stemflow on the forest floor.
Many methods exist to measure canopy interception. The most often used method is by measuring rainfall above the canopy and subtract throughfall and stem flow [1] ). However, the problem with this method is that the canopy is not homogeneous, which causes difficulty in obtaining representative throughfall data.
A method employed to avoid this problem is covering forest floor with plastic sheets and collecting the throughfall. [2] [3] [4] The disadvantage of this method is that it is not suitable for long periods, because in the end the trees will dry from water shortage, and the method is also not applicable for snow events.
The method by Hancock and Crowther [5] avoided these problems by making use of the cantilever effect of branches. If leaves on a branch hold water, it becomes more heavy and will bend. By measuring the displacement, it is possible to determine the amount of intercepted water. this method was refined in 2005 by making use of strain gauges. [6] However, the disadvantages of these methods are that only information about one single branch is obtained and it would be quite laborious to measure an entire tree or forest.
Hydrology is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydrologist. Hydrologists are scientists studying earth or environmental science, civil or environmental engineering, and physical geography. Using various analytical methods and scientific techniques, they collect and analyze data to help solve water related problems such as environmental preservation, natural disasters, and water management.
A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level, formally described in the International Cloud Atlas (2017) as silvagenitus. Cloud forests often exhibit an abundance of mosses covering the ground and vegetation, in which case they are also referred to as mossy forests. Mossy forests usually develop on the saddles of mountains, where moisture introduced by settling clouds is more effectively retained.
Evapotranspiration (ET) refers to the combined processes which move water from the Earth's surface into the atmosphere. It covers both water evaporation and transpiration. Evapotranspiration is an important part of the local water cycle and climate, and measurement of it plays a key role in agricultural irrigation and water resource management.
A rain gauge is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a predefined area, over a period of time. It is used to determine the depth of precipitation that occurs over a unit area and measure rainfall amount.
A stream gauge, streamgage or stream gauging station is a location used by hydrologists or environmental scientists to monitor and test terrestrial bodies of water. Hydrometric measurements of water level surface elevation ("stage") and/or volumetric discharge (flow) are generally taken and observations of biota and water quality may also be made. The locations of gauging stations are often found on topographical maps. Some gauging stations are highly automated and may include telemetry capability transmitted to a central data logging facility.
In hydrology, discharge is the volumetric flow rate of a stream. It equals the product of average flow velocity and the cross-sectional area. It includes any suspended solids, dissolved chemicals like CaCO
3(aq), or biologic material in addition to the water itself. Terms may vary between disciplines. For example, a fluvial hydrologist studying natural river systems may define discharge as streamflow, whereas an engineer operating a reservoir system may equate it with outflow, contrasted with inflow.
Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna, funga, and ecosystems in forests. The management of forests is known as forestry, silviculture, and forest management. A forest ecosystem is a natural woodland unit consisting of all plants, animals, and micro-organisms in that area functioning together with all of the non-living physical (abiotic) factors of the environment.
Leaf area index (LAI) is a dimensionless quantity that characterizes plant canopies. It is defined as the one-sided green leaf area per unit ground surface area in broadleaf canopies. In conifers, three definitions for LAI have been used:
Interception refers to precipitation that does not reach the soil, but is instead intercepted by the leaves, branches of plants and the forest floor. It occurs in the canopy, and in the forest floor or litter layer. Because of evaporation, interception of liquid water generally leads to loss of that precipitation for the drainage basin, except for cases such as fog interception, but increase flood protection dramatically, Alila et al., (2009).
In biology, the canopy is the aboveground portion of a plant cropping or crop, formed by the collection of individual plant crowns. In forest ecology, canopy refers to the upper layer or habitat zone, formed by mature tree crowns and including other biological organisms. The communities that inhabit the canopy layer are thought to be involved in maintaining forest diversity, resilience, and functioning. Shade trees normally have a dense canopy that blocks light from lower growing plants.
Infiltration is the process by which water on the ground surface enters the soil. It is commonly used in both hydrology and soil sciences. The infiltration capacity is defined as the maximum rate of infiltration. It is most often measured in meters per day but can also be measured in other units of distance over time if necessary. The infiltration capacity decreases as the soil moisture content of soils surface layers increases. If the precipitation rate exceeds the infiltration rate, runoff will usually occur unless there is some physical barrier.
In hydrology, stemflow is the flow of intercepted water down the trunk or stem of a plant. Stemflow, along with throughfall, is responsible for the transferral of precipitation and nutrients from the canopy to the soil. In tropical rainforests, where this kind of flow can be substantial, erosion gullies can form at the base of the trunk. However, in more temperate climates stemflow levels are low and have little erosional power.
Ecological thinning is a silvicultural technique used in forest management that involves cutting trees to improve functions of a forest other than timber production.
Pan evaporation is a measurement that combines or integrates the effects of several climate elements: temperature, humidity, rain fall, drought dispersion, solar radiation, and wind. Evaporation is greatest on hot, windy, dry, sunny days; and is greatly reduced when clouds block the sun and when air is cool, calm, and humid. Pan evaporation measurements enable farmers and ranchers to understand how much water their crops will need.
The following outline is provided as an overview of and topical guide to hydrology:
Catchment hydrology is the study of hydrology in drainage basins. Catchments are areas of land where runoff collects to a specific zone. This movement is caused by water moving from areas of high energy to low energy due to the influence of gravity. Catchments often do not last for long periods of time as the water evaporates, drains into the soil, or is consumed by animals.
DPHM-RS is a semi-distributed hydrologic model developed at University of Alberta, Canada.
Forest floor interception is the part of the (net) precipitation or throughfall that is temporarily stored in the top layer of the forest floor and successively evaporated within a few hours or days during and after the rainfall event. The forest floor can consist of bare soil, short vegetation or litter. This throughfall is especially rich in nutrients which makes its redistribution into the soil is an important factor for the ecology and water demand of surrounding vegetation. As a hydrological process it is crucial for water resource management and climate change.
In forestry, a tree crown measurement is one of the tree measurements taken at the crown of a tree, which consists of the mass of foliage and branches growing outward from the trunk of the tree. The average crown spread is the average horizontal width of the crown, taken from dripline to dripline as one moves around the crown. The dripline is the outer boundary to the area located directly under the outer circumference of the tree branches. When the tree canopy gets wet, any excess water is shed to the ground along this dripline. Some listings will also list the maximum crown spread which represents the greatest width from dripline to dripline across the crown. Other crown measurements that are commonly taken include limb length, crown volume, and foliage density. Canopy mapping surveys the position and size of all of the limbs down to a certain size in the crown of the tree and is commonly used when measuring the overall wood volume of a tree.
The Soil Dryness Index (SDI) uses daily rainfall and maximum temperature from local meteorological stations to estimate soil dryness across tens of kilometers. It estimates the millimeters of rain needed to fill the soil with water. The term was coined by Mount to focus attention on how useful a reliable measure of soil dryness is for flood and fire forecasting and management. Tasmanian government departments, businesses and land managers have used the SDI for these purposes for over 50 years and it is published daily by the Tasmanian Fire Service. Other states in Australia also make use of the SDI.