Stream Erosion

Stream erosion is when water flowing through a channel has the ability to transport sediment to it from hill slopes and erode its banks and bed to produce sediment to transport. Sediment is the varied materials, organic and inorganic that can be carried away by water, wind or ice. The volume of flow normally depends on the amount of sediment being taken down stream. Eighty-five to ninety percent of the total sediment transported to sea has been due to rivers. Seven percent is transported by glaciers, whereas only one to two percent by groundwater and ocean waves, and less than one percent by both wind and volcanoes. River networks are multiple branching systems, beginning with tiny rivulets flowing downhill during rainstorms that join into rills and gullies and eventually into creeks and streams that continue to flow even when the rain has stopped.  These are fed by water that has soaked into the soil and that then slowly reemerges from stream banks to maintain the base flow of the stream. Rivers primarily create the most erosion . They acquire soil and weathered rock debris from hill slopes and valley walls, ranging in grain size from fine mud, sand, and gravel to huge boulders. Most erosion by rivers is accomplished during the brief intervals of high discharge and flooding. Rivers flow is not only faster but also deeper and wider, and it is also much muddier.  Due to the increase in turbulence in a deep fast flowing stream, the river can carry up to one hundred to one thousand, times as much water. That water carries up to one thousand times as much mud than at low flow; this means more sediment is being moved.

There are three major modes of sediment transport. The first mode is solution load; this is when dissolved material is carried by a river. This often happens in areas where the geology is limestone and is dissolved by slightly acidic water. Generally this is higher where much of the flow is derived from groundwater pathways, which allow water to stay in contact with rock for long periods. In the solution load, the sediment will not settle to the bottom of a waterway during a low or no flow period. These particles remain in permanent suspension as they are small enough to bounce off water and stay afloat.

The next mode of sediment transportation is suspended sediment/ suspended load. This is sediment that can be found in nearly any body of water, carried along by the water flow. There is an overlap between these two. Suspended sediment are any particles found in the water column, whether the water is flowing or not. The suspended load is the amount of sediment carried downstream within the water column by the water flow. Suspended loads require moving water, as the water flow creates small upward currents that keep the particles above the bed.  The size of particles that can be carried as suspended load is dependent on the flow rate. Larger particles are more likely to fall thought the upward currents to the bottom, unless the flow rate increases.

Bed load is the last mode of sediment transportation. Bed load is the portion of sediment transport that rolls, slides or bounces along the bottom of a waterway. “Bed load is transported in two ways, traction, which is a scooting and rolling of particles along the bed, and saltation, a bouncing like movement.” This sediment is not truly suspended, as it sustains intermittent contact with the streambed, and the movement is neither uniform nor continuous. Bed load occurs when the force of the water flow is strong enough to overcome the weight and cohesion of the sediment. While the particles are pushed along, they typically do not move as fast as the water around them, as the flow rate is not great enough to fully suspend them. Bed load transport can occur during low flows with smaller particles or at high flows resulting in larger particles. Around 5-20% of total sediment transport is a result of bed load. 

http://www.earthonlinemedia.com/ebooks/tpe_3e/fluvial_systems/geologic_work_of_streams.html

http://www.tulane.edu/~sanelson/eens1110/streams.htm

http://www.geologyclass.org/Stream%20Concepts.htm

Wetlands

What are wetlands? Wetlands defined “are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface.” Wetlands can be found in all types of biomes, but vary due to regional and local differences in soils, vegetation, climate, human disturbance and other factors. Wetlands are one part of the foundation our nations water resources and are one of the most vital contributions to the health of waterways and communities that are downstream. Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including, during the growing season. There are both tidal wetlands and non-tidal wetlands. Tidal wetlands in the United States are found along the Atlantic, Pacific, Alaskan and Gulf coasts. They are close to where the sea water mixes with fresh water to form an environment of varying salinity. Many sallow coastal areas are vegetated mud flats or sand flats. This is a difficult environment for most plants to grow. However, some plants such as grass like plants have been able to successfully adapt to this environment. Non-tidal wetlands are most common in floodplains along rivers and streams. Inland wetlands include marshes and wet meadows dominated by herbaceous plants, swamps dominated by shrubs, and wooded swaps dominated by trees.

Why are wetlands so important? Wetlands are important for a multitude of reasons. One reason being is that they play a large role in our ecosystems. Wetlands can prevent flooding by holding/ absorbing water much like a sponge. By wetlands being able to do this is helps keep river levels normal and not only filter but also purify the surface water. Wetlands also release vegetative matter into rivers, which helps feed the organisms living in the water. Furthermore, wetlands help to counter balance the human effect on rivers by rejuvenating them and the surrounding ecosystems. Another reason why wetlands are important is that they provide significant economic, social and cultural benefits. They are important for primary products such as pastures, timber, fish and they support recreational and tourist activities. Wetlands support agricultural activities by providing a source of water for irrigation and livestock for domestic consumption. Recreational activities that inland wetlands are popular for are swimming, boating, fishing and camping to name a few. They also help reduce the impacts of storm damage, they maintain good water quality in rivers, recharge ground water, store carbon, help stabilize climatic conditions and control pests. Wetlands are also homes to many plants and animals, wetlands provide essential habitat for rare or important species.

What is the Ramsar Convention? “The Convention on Wetlands, called the Ramsar Convention, is an intergovernmental treaty that provides the framework for national action and international cooperation for the conversation and wise use of wetlands and their resources.” Ramsar is the oldest of the modern global intergovernmental agreements. The treaty was negotiated through the 1960s by the countries and non-governmental organizations concerned about the increasing loss of degradation of wetland habitat for migratory water birds. Their mission is the conservation and wise use of all wetlands through local and national actions and international cooperation, as a contribution towards achieving sustainable development throughout the world. In 2015 a list came out of 37 designated wetlands of international importance in the United States.  One of the sites on the list is the Olentangy River Wetland Research Park located near Ohio State University. The Research Park is a large scale aquatic research facility.

http://www.ohwetlands.org/ramsar-wetlands-of-international-importance.html

https://rsis.ramsar.org/

http://www.wetlands.org/Whatarewetlands/tabid/202/Default.aspx

Urbanization

What is urbanization one might ask? Urbanization refers to the concentration of human populations into discrete areas, leading to transformation of land for residential, commercial; industrial and transportation purposes.  The word urbanization is becoming more like a word associated with a city. Urbanization is when populations of people grow; the population of a play may become too big and spill over from cities to nearby areas. “Urbanization in America saw the emergence of many new towns and cities which became even larger as more and more people, attracted by employment possibilities, begin living and working in towns and cities”

What are the factors of urbanization?  One factor of urbanization is population growth which contains three components natural growth of urban population, rural urban migration and the reclassification of areas that are considered rural. Natural increase provides a base for urban population growth rates and rural urban migration reclassification supplement this growth.  Another factor is poverty is another factor; in this case the needs of humanity are not being met.  Poverty is happening everywhere both in developed and developing countries. These individuals do not have the money to take care of their basic needs such as their physical self, their diet, housing, water and sanitation.

Why do we care? “Urbanization has the potential to usher in a new era of well-being, resources efficiency and economic growth.” We care because urban developments have increased dramatically in recent decades, and this increase is projected to continue. The United States developed land is projected to increase from 5.2% to 9.2% of the total land base within the next 25 years. On a national scale, urbanization affects relatively little land cover, but it has a significant ecological footprint. This means that even small amounts of urban development can have large effects on stream ecosystems. Another reason we care is because cities generate economic growth and cultural development and can offer many benefits to the citizens. Cities economic growth is rapidly higher than rural areas. Urban growth has the opportunity to connect more people to water and electricity, making the citizens healthier and therefore more productive. If urbanization is poorly managed will only add on to existing challenges, risks can include fast spreading diseases, gang violence and possible terrorism.

Where is urbanization happening in the world today?

More than one half of the world’s population lives in urban areas, and virtually all countries of the world are becoming increasingly urbanized. Urbanization is a global phenomenon that has nonetheless very different expressions across regions and development levels. This includes wealthier countries and those of Latin America and the Caribbean they have already a large proportion of their population residing in urban areas. Whereas countries such as, Africa and Asia are still mostly rural, they will urbanize faster than other regions over the coming decades. These trends are changing the landscape of human settlement, with significant implications for living conditions, the environment and development in different parts of the world. Daniel Rundue contributor to the Forbes article Urbanization Will Change the (Developing) World states that “96 percent of all urbanization by 2030 will occur in the developing world.”  With everyone looking to urbanize and move to the surrounding cities we need to consider a few things. The major issue rising concerns is do these areas have enough food, water and energy consumption to support the capacity or soon to be capacity of the cities.

http://www.american-historama.org/1881-1913-maturation-era/urbanization-in-america.htm

http://www.forbes.com/sites/danielrunde/2015/02/24/urbanization-development-opportunity/

http://www.unfpa.org/urbanization