Glossary

h
half-lifesearch for term
The half-life of a herbicide describes the length of time it takes for 50% of the herbicide to break down to secondary compounds.
herbaceoussearch for term
Having little or no woody tissue.
herbicidesearch for term
A chemical substance used to destroy or inhibit the growth of plants, especially weeds.
herbicide precipitationsearch for term
Falling out of solution and sinking to the bottom.
herbivoroussearch for term
plant-eating
humic acidsearch for term
Produced when organic matter such as dead leaves and plant material decay. Humic acids can color water so that it appears reddish or reddish-brown, even black.
hydraulic conductivitysearch for term
Ability of a canal to transport water. Water-handling capacity.
hydraulic gradientsearch for term
The movement of water downward along the horizontal slope of the subsurface bedding plane.
hydrologic cyclesearch for term
The sequence of conditions through which water passes from vapor in the atmosphere through precipitation on land and water surfaces and then back to the atmosphere through evaporation and transpiration.
hydrolysissearch for term
Breaking down in water.
hydrostatic headsearch for term
A measure of water pressure. The pressure at a given point in a liquid measured in terms of the vertical height of a column of the liquid needed to produce the same pressure.
hypereutrophicsearch for term
An aquatic system with high productivity and very high nutrients.
hypolimnionsearch for term
the part of a lake below the thermocline made of water that is stagnant and of essentially uniform temperature except during the period of overturn.
hypoxiasearch for term
A deficiency of oxygen.