Chapter: What is the legal term for land bordering a river or stream in Louisiana? (EN)

Riparian Law and Louisiana’s Civil Law Tradition

Louisiana’s legal framework regarding land bordering rivers and streams is deeply rooted in its unique civil law tradition, derived from Roman and French legal systems, rather than English common law, which predominates in most other U.S. states. This distinction profoundly impacts the terminology and principles governing riparian rights and ownership along waterways.

Defining Riparian Rights

Riparian rights, in general, concern the legal rights of landowners whose property borders a body of water (river, stream, lake, or ocean). These rights can include:

• Access Rights: The right to access the waterbody from the property.
• Use Rights: The right to use the water, subject to certain restrictions and reasonable use principles.
• Accretion Rights: The right to gain land that gradually forms along the bank due to natural processes.
• Erosion Rights: The right to claim land that was previously lost to erosion but is subsequently restored by natural processes.

The Legal Term: “Bank” or “Shore” (and their French Equivalents)

In Louisiana, while the general concept of riparian rights is understood, the specific legal term used to designate the land bordering a river or stream is the bank or shore. It is crucial to understand the nuances in Louisiana law regarding ownership and usage of these “banks.”

• Louisiana Civil Code: The Louisiana Civil Code Articles 450-452 address the public nature of navigable rivers and streams. These articles define the “banks” or “shores” of navigable rivers or streams as public things. The relevant French terms are berge (bank) and rivage (shore).

• Article 450: “Public things are owned by the state or its political subdivisions in their capacity as public persons. Public things that belong to the state are such as running waters, the waters and bottoms of natural navigable water bodies, the territorial sea, and the seashore.”

• Article 451: “The banks of navigable rivers or streams are public things. The banks are that space of ground which is between the ordinary low and the ordinary high stage of the water. Nevertheless, when the banks are of such nature that they cannot be used for public purposes, the owner of the soil has the right to enclose them, provided that he does not thereby impede the navigation of the river or stream.”

• Article 452: “The use of the banks of navigable rivers or streams is public; everyone has the right freely to bring his vessels to land there, to make fast the same to the trees which are there planted, to unload his vessels, to dry his nets, and the like.”

Scientific Principles Underpinning Bank Formation

Understanding the dynamic nature of river banks requires an understanding of basic fluvial geomorphology. Several physical processes contribute to the formation and alteration of riverbanks:

1. Erosion: The wearing away of soil and rock by the action of water. Erosion rate ($E$) can be modeled by:

   $E = k \cdot S \cdot Q$

   where:

   • $E$ is the erosion rate (e.g., kg/s)
   • $k$ is an erodibility coefficient (dependent on soil type and vegetation)
   • $S$ is the slope of the bank
   • $Q$ is the discharge of the river (m³/s)

2. Sediment Transport: The movement of eroded material by the river. The capacity of a river to transport sediment ($T_c$) is related to flow velocity ($v$) and depth ($d$) according to empirical relations (e.g., Meyer-Peter and Müller formula):

   $T_c = A ( \tau - \tau_c)^{1.5}$

   where:

   • $A$ is a coefficient related to sediment properties
   • $\tau$ is the bed shear stress ($\tau = \rho g d S$, where $\rho$ is water density, $g$ is gravitational acceleration, and $S$ is channel slope)
   • $\tau_c$ is the critical shear stress for sediment entrainment.

3. Sediment Deposition (Accretion): The settling of sediment when the river’s flow velocity decreases. Deposition is more likely to occur in areas of lower slope and reduced flow velocity, such as along the inside bends of meandering rivers.

4. Bank Stability: The resistance of a bank to erosion. Bank stability is influenced by:

   • Soil Type: Clay-rich soils tend to be more cohesive and resistant to erosion than sandy soils.
   • Vegetation: Root systems bind the soil together, increasing bank stability.
   • Bank Angle: Steeper banks are more susceptible to collapse.
   • Water Content: Saturated soils are often weaker than unsaturated soils.

Practical Applications and Experiments

• River Bank Stabilization Projects: Engineers use various techniques to stabilize riverbanks and prevent erosion, including:

  • Riprap: Placement of large rocks along the bank to protect it from erosion.
  • Vegetation Planting: Establishing vegetation along the bank to bind the soil and reduce erosion.
  • Bioengineering Techniques: Using a combination of vegetation and engineered structures to stabilize the bank.
  • Gabions: Wire mesh cages filled with rocks to create a flexible, erosion-resistant structure.

• Laboratory Experiments: Flume experiments can be conducted to study the effects of different factors on bank erosion. These experiments typically involve:

  1. Constructing a miniature river channel (flume).
  2. Creating artificial riverbanks with different soil types and vegetation.
  3. Varying the flow rate and water level in the flume.
  4. Measuring the rate of bank erosion over time.

Important Discoveries and Breakthroughs

• The understanding of the role of vegetation in bank stability: Early soil erosion studies highlighted the importance of vegetation in preventing soil loss. This led to the development of bioengineering techniques for bank stabilization.
• The development of mathematical models for sediment transport: The Meyer-Peter and Müller formula (mentioned above) was a significant breakthrough in understanding the relationship between flow conditions and sediment transport.
• The recognition of the importance of hydraulic roughness in river flow: The Manning equation relates flow velocity to channel slope, hydraulic radius, and a roughness coefficient (n), which accounts for the resistance to flow caused by channel irregularities and vegetation. This has helped to improve the accuracy of river flow models.

Scientific Basis for Legal Disputes

Disputes over riparian rights often arise due to changes in riverbank location caused by natural processes such as erosion and accretion. Scientific evidence, including historical surveys, aerial photographs, and hydrological data, is often used in legal proceedings to determine the original location of the bank and the extent of any land gains or losses. Understanding the scientific principles governing bank formation and erosion is crucial for resolving these disputes fairly and accurately.