Unchecked rill and gully formation can lead to several long-term environmental impacts on a landscape. As rills evolve into gullies, they can significantly alter the topography, leading to land degradation. This degradation manifests in the loss of fertile topsoil, reduced agricultural productivity, and potentially the transformation of productive land into barren areas. The deepening and widening of gullies disrupt natural drainage patterns, which can affect local hydrology, leading to altered groundwater recharge rates and potentially affecting local water supplies. Gully formation can also result in habitat destruction, as it disturbs the native vegetation and wildlife, leading to a loss of biodiversity. The sediment transported by these processes can accumulate in rivers, lakes, and reservoirs, impacting water quality and aquatic ecosystems. This sedimentation can reduce the storage capacity of reservoirs, affect the health of aquatic habitats, and increase the cost of water treatment. In addition, the visual aesthetic of the landscape is altered, which can impact recreational values and tourism. Therefore, the long-term environmental impacts of unchecked rill and gully formation are extensive, affecting not just the physical landscape but also the ecological, economic, and social aspects of the area.

Urbanisation significantly impacts the processes of rainsplash erosion, surface runoff, and rill formation. The replacement of natural, permeable surfaces with impermeable materials like concrete and asphalt drastically alters the hydrological characteristics of an area. In urban environments, the absence of soil and vegetation reduces the natural infiltration of rainwater. Consequently, more water is available for surface runoff, increasing the volume and velocity of the flow. This urban runoff tends to carry a higher sediment load, as it gathers pollutants and debris from urban surfaces. The increased flow and sediment load enhance the erosive potential of runoff, leading to more severe and rapid soil erosion in areas where natural ground is still exposed. Furthermore, urban drainage systems often channelise runoff, concentrating the flow and potentially exacerbating rill and gully formation in susceptible areas. In addition, the heat island effect in urban areas can alter local weather patterns, potentially increasing the frequency and intensity of rainfall events, further intensifying these processes. Therefore, urbanisation not only amplifies the severity of these erosional processes but also introduces new challenges in managing water and soil resources.

Soil composition plays a crucial role in the process and impact of rainsplash erosion. Different soil types, characterized by their particle size and cohesion, respond differently to the impact of raindrops. For instance, sandy soils, with larger, loosely held particles, are more prone to displacement upon the impact of raindrops. However, the low cohesion and large pore spaces in sandy soils often result in less surface sealing, which somewhat mitigates further erosion. In contrast, clayey soils, with smaller, more cohesive particles, are less susceptible to initial displacement but are more prone to surface sealing. This sealing effect significantly reduces water infiltration, leading to increased surface runoff and potential for further erosion. Loamy soils, with a balance of sand, silt, and clay, exhibit intermediate behaviour. The organic matter content in soils also influences rainsplash erosion. Soils rich in organic matter tend to have better structure and cohesion, thus reducing susceptibility to rainsplash erosion. The diversity in soil composition across different landscapes therefore results in varied patterns and extents of rainsplash erosion, impacting soil stability and fertility.

Vegetation plays a vital role in mitigating surface runoff and soil erosion, acting as a natural barrier against erosive forces. The presence of vegetation, including grass, shrubs, and trees, significantly reduces the impact of rainsplash erosion by intercepting raindrops before they hit the soil surface. This interception diminishes the kinetic energy of raindrops, thereby reducing their potential to detach soil particles. Additionally, the root systems of plants enhance soil cohesion, making it more resistant to erosion. Roots bind soil particles together, creating a more stable soil structure that is less prone to being carried away by surface runoff. Vegetation also increases soil infiltration capacity by improving soil porosity, which reduces the volume of surface runoff. Furthermore, plant cover reduces the velocity of surface runoff by creating physical obstacles, thus decreasing its erosive power. As a result, areas with dense vegetation cover often experience significantly lower rates of soil erosion compared to bare or sparsely vegetated areas. This underlines the importance of maintaining and promoting vegetation cover as a sustainable strategy for soil conservation and erosion control.

Human activities can both exacerbate and mitigate the effects of surface runoff and soil erosion. Exacerbation often occurs through land-use practices that reduce vegetation cover, such as deforestation, overgrazing, and unsustainable agricultural practices. These activities diminish the soil's ability to absorb water, leading to increased surface runoff and erosion. Construction activities, especially in urban areas, can also exacerbate these effects by increasing impervious surfaces, thereby reducing infiltration and increasing runoff volume and velocity.

On the other hand, human interventions can mitigate these effects through several soil conservation and land management practices. Planting vegetation, especially in erosion-prone areas, can significantly reduce runoff and soil loss. This includes reforestation, cover cropping, and the establishment of grass waterways. Constructing terraces on sloping land can reduce the slope length and gradient, thereby decreasing runoff velocity and soil erosion. The use of permeable paving materials in urban areas allows for better water infiltration, reducing runoff. Additionally, implementing rainwater harvesting and stormwater management practices can control runoff and reduce its erosive potential. Therefore, human activities have a profound impact on surface runoff and soil erosion, and responsible land management practices are essential to mitigate these effects.