Chapter 1
Natural resources engineering opportunities

Water, soil, air, plants, animals, other people, are each necessary for our existence. They form our collective environment. Since the dawn of history, humankind has been cultivating food and fiber, domesticating animals, and developing resources. Providing tools facilitating "dressing and keeping" the planet while meeting feed, food, and fiber needs is the overarching vision for this text. Since the 2002 edition, bioenergy production, sustainability, and climate-change pressures have stimulated increased realization of the necessity for responsible natural resource engineering.

Where do we begin? The study of natural resources engineering starts primarily with the study of the physical, biological, and chemical modalities operating in the environment. Physical effects are manifest in the hydrologic cycle (see NOAA, 2014). In a survey of the holdings of the University of Georgia Libraries under "land use change," some 8000 articles discuss the hydrologic cycle. The near uniform distribution of books and microfilms dated from 1833 to 2014. There were an additional 500 items going back to 1569. Land-use change has exercised public debates for many years. According to Biswas (1970), philosophers have documented natural forces since the time of Hammurabi (circa 1700 B.C.E.). Solomon (circa 900 B.C.E.) made one of the most elegant statements pointing toward the hydrologic cycle:

A generation goes, and a generation comes, but the earth remains forever. Also, the sun rises and the sun sets; and, hastening to its place, it rises there again. Blowing toward the south, then turning toward the north, the wind continues swirling along. On it circular courses the wind returns. All the rivers flow into the sea yet the sea is not full. To a place where the rivers flow, there they flow again.

Ecclesiastes (1:4-7)

Humankind establishes boundaries in time and space not respected by water, soil, and air. People cannot completely control the biotic or chemical components. We focus mainly on water and soil. Impacts spread across humankind's boundaries, spatially and temporal. Effects become manifest in the face of population increases. Developing nations desire to achieve a standard of living of developed countries, which results in additional pressure. Society looks for the path of moderation between development and conservation. Engineers and other professionals contribute to the identification of that moderate path. The text omits the components of natural resource engineering that link heavily to the airshed.1 The text also does not present other well-developed topics in classic environmental engineering curricula such as waste management, even though all these satisfy the adapted definition of Natural Resources Engineering.

GOALS

• To define fundamental issues and scales associated with Natural Resources Engineering.
• To evaluate how land use is changing in response to societal forces and visualize the resulting opportunities for Natural Resource Engineering.
• To overview the scope of Natural Resources Engineering.

1.1 Definitions

1. Natural Resources Engineering - the design of planned activities complementary to or in opposition to physical and societal forces leading to modifications of the soil, water, biota, and air environment. The natural forces relate to the hydrologic cycle. Societal forces stem from the desires of people. The Natural Resources Engineer practices on scales ranging from the field, farm, to basins. The purpose is resource development and environmental management.
2. Ecological Engineering - natural resources engineering practiced largely at the basin scale. Ecological Engineers come from an ecology background, but practice the same art and science as a Natural Resources Engineer.

The foregoing definition of Natural Resources Engineer broadens the scope of natural resources from resource extraction. The text emphasizes more general activities such as crop production and urban development, while the definition also includes activities such as bioremediation and bioconversion. The following terms often appear in the Natural Resources Engineering literature.

1. Biological remediation (bioremediation) - the application of plant materials, organic amendments, and microbial organisms in order to sequester or transform toxins.
2. Bioconversion - the biologically mediated physical and chemical conversion of municipal, agricultural, and industrial organics to useful products.
3. Climate change - the established notion that temperature and precipitation patterns evolve over time as a rsult of solar irradiation changes, volcanism, and other earth movements, and possibly human-induced changes: urban heat islands, impacts of reservoir installation, sea-level rise, and changes in monsoonal rainfall timing appear to be the documented climate-change effects that directly or indirectly intersect topics discussed in this text.
4. Farm, field, and factory scale - refers to typical problem size: the problem scope lies among the regional and greenhouse, room, or microbial scales.
5. Hydrology - the scientific study of water: the properties, distribution, constituents, and transport in the atmospheric, surface, and subsurface realms.
6. Urban agriculture - the development of organic agricultural production, often within urban areas or on the urban fringe.

1.2 The hydrologic cycle and the water-soil-air-biotic continuum

Water and wind are the driving forces for production and pollution. Thus, one must be concerned with the hydrologic cycle. For example, consider the continental United States. The equivalent depth of water passing over the United States in the atmosphere is 300 in. Average annual precipitation over the US land mass is about 30 in (762 mm), partitioned as follows:

• 26 in (660 mm) as rain;
• 4 in (102 mm) as snow, sleet, hail;
• 9 in (229 mm) percolate to groundwater or runs off;
• 21 in (533 mm) returns to the atmosphere;
• 0.73 in (18.5 mm) is consumptively used.

Agriculture consumes 83% of the consumptively used water, but competition is increasing. Agricultural irrigation requires about 40% of consumptively used water. About 40% of the atmospheric return is due to inefficient irrigation. Some corresponding partitions for the world are (Maidment, 1993):

• 31 in (800 mm) falls as precipitation;
• 12 in (320 mm) as runoff to the land;
• 5 in (130 mm) as runoff to the oceans.

Figure 1.1 schematically shows the hydrologic cycle and highlights water management engineering addressed in this work.

• Water falls to earth as precipitation: rain, drizzle, snow, sleet, hail; water also forms directly by condensation - dew.
• Plants may intercept precipitation reaching the ground surface. Water may infiltrate and percolate into the soil, run off the surface, or evaporate.
• Evaporation may occur directly from the precipitation, from plant leaves (wetted leaves and due to transpiration), from the soil surface, from storage structures, from streams and water bodies and the ocean.
• Winds transport moisture, wind-eroded and human-activity-sourced particulates, and odors.
• Plants use infiltrated water (transpiration).

Water may seep into the groundwater, streams, and surface water bodies. It may also move laterally after infiltrating and reappear on the surface at some point downslope (interflow). A complete development of wind erosion and air quality aspects are left to other texts.

Figure 1.1 Schematic view of the hydrological cycle and related engineering topics associated with Natural Resources Engineering.

Standard hydrologic measurements include the following:

• precipitation, by rain and snow gages;
• accumulated snow, by snow surveys;
• runoff at outlets, using various weirs or related devices;
• evaporation measured using evaporation pans;
• evapotranspiration, by lysimeters or more advanced techniques;
• groundwater level, with monitoring wells and piezometers;
• wind speed and direction, with anemometers and wind vanes;
• humidity, with hygrometers or other electronic means; and,
• solar radiation, with radiometers.

Class A weather stations and some state environmental networks contain instrumentation for many of these measurements. A visit to the US Geological Survey (USGS) home page provides much information relating to runoff and groundwater levels at sites around the United States.

1.3 Changing land uses due to societal forces

In the United States we are diverting forests and prime farmlands to urban developments, designated wetlands, reservoirs, and the like. Change in land use implies a change in land ownership. Change in land use may trigger legally mandated assessments related to environmental appropriateness for the intended use. Requests for financial assistance for making the change may trigger assessments. A visit to the National Resources Inventory of the US Department of Agriculture (USDA, 2013) provides a summary of current trends in the United States.

The application of soil conservation practices to cropland area in the United States is increasing. Total rural land in the United States has decreased about 3% from 1982 to 2010: from approximately to acres. Of the...